Engine Exhaust System GMC Sierra 2500

Fastener Tightening Specifications

Fastener Tightening Specifications

Scheme 1

Symptoms - Engine Exhaust

1. Review the exhaust system description in order to familiarize yourself with the exhaust system components and the intended function of the components. Refer to «Exhaust System Description»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system__exhaust-system-description) .
2. All diagnostics on a vehicle should follow a logical process. Strategy Based Diagnostics is a uniform approach for repairing all systems. The diagnostic flow is the place to start when repairs are necessary and may always be used in order to resolve a system problem. For a detailed explanation, refer to «Strategy Based Diagnosis»(/gmc/sierra-2500/2012-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) .

Visual/Physical Inspection

1. Inspect for aftermarket or non-OEM devices such as, but not limited to; tailpipe extensions, headers, and exhaust cutouts. Any aftermarket exhaust system devices could affect the operation and proper performance of the exhaust system.
2. Verify the exact operating conditions under which the concern exists. Note factors such as engine RPM, engine temperature, engine load, and frequency of concern.
3. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause any symptom.

Intermittent

Test the vehicle under the same conditions that the customer reported in order to verify the system is operating as designed.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. Loss of power Refer to «Restricted Exhaust»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system)
2. Poor acceleration Refer to «Restricted Exhaust»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system)
3. Poor fuel economy Refer to «Restricted Exhaust»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system)
4. Excessive smoke diesel Refer to «Restricted Exhaust»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system)
5. Exhaust hissing noise Refer to «Exhaust Leakage»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system__exhaust-leakage)
6. Exhaust popping noise Refer to «Exhaust Leakage»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system__exhaust-leakage)
7. Exhaust rattle noise Refer to «Exhaust Noise»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system__exhaust-noise)
8. Loud exhaust noise Refer to «Exhaust Noise»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system__exhaust-noise)
9. Exhaust buzz, groan, hum noise Refer to «Exhaust Noise»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system__exhaust-noise)

Diagnostic Aids

Note. Do not replace a restricted particulate filter. Repair the engine condition that clogged the particulate filter, and then attempt to perform a service regeneration. Refer to Diesel Particulate Filter (DPF) Service Regeneration .

If the vehicle is equipped with a 6.6 L diesel engine do not perform this diagnostic. The exhaust system does not have a location for installing the J 35314-A exhaust back pressure gauge. Instead remove the suspect component, operate the vehicle, verify for improved performance. If performance is improved then replace the faulty component.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. 4 The exhaust system has very low back pressure under normal conditions. If the exhaust system is restricted, a significant increase in the exhaust pressure is noticed on the J 35314-A exhaust back pressure gauge. Removing the heated oxygen sensor (HO2S) sensor may set a DTC. When finishing this diagnostic table, be sure to clear all codes.
2. 5 This step will isolate the catalytic converter from the remainder of the exhaust system.
3. 8 Confirming that the condition has been fixed is essential. If the symptom still exists and the vehicle has a dual exhaust system, proceed to Step 2 and repeat diagnostic procedure on the opposite exhaust pipe.

Restricted Exhaust

Exhaust Leakage

Exhaust Leakage

Exhaust Noise

Exhaust Noise

Exhaust Manifold Replacement - Left Side (V8)

Special Tools

J 42640 Steering Column Anti-Rotation Pin

Removal Procedure

1. Install the J 42640 steering column anti-rotation pin into the steering column lower access hole.
2. Remove the left wheelhouse liner. Refer to «Front Wheelhouse Liner Replacement - Left Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Left Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
3. Fully raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
4. Remove the catalytic converter to exhaust manifold nuts. (1500 series shown, 2500 series similar).
5. Lower the vehicle part way in order to work through the wheel opening.
6. Remove the spark plug wires from the spark plugs. Twist the spark plug wire boot a 1/2 turn. Pull only on the boot in order to remove the wire from the spark plug.
7. Remove the spark plug wires from the ignition coils. Twist the spark plug wire boot a 1/2 turn. Pull only on the boot in order to remove the wire from the ignition coil.
8. Mark the relationship of the upper intermediate steering shaft to the steering column.
9. Remove the steering shaft coupling bolt (2) and nut (1) from the upper intermediate steering shaft.
10. Separate the upper intermediate steering shaft (3) from the steering column, position both shafts out of the way.
11. Remove the exhaust manifold bolts, and exhaust manifold.
12. Remove and discard the exhaust manifold gasket.
13. Remove and discard the catalytic converter seal.
14. If replacing the exhaust manifold, remove the exhaust manifold heat shield bolts, and shield from the exhaust manifold.

Installation Procedure

Note. Tighten the exhaust manifold bolts as specified in the service procedure. Improperly installed and/or leaking exhaust manifold gaskets may affect vehicle emissions and/or On-Board Diagnostic (OBD) II system performance. The cylinder head exhaust manifold bolt hole threads must be clean and free of debris or threadlocking material. Do not apply sealant to the first 3 threads of the bolt.

1. If the exhaust manifold was replaced, position and install the exhaust manifold heat shield, and bolts to the exhaust manifold. Tighten Tighten the bolts to 9 (80 lb in).
2. Clean the threads of the exhaust manifold bolts.
3. Apply a 5 mm (0.2 in) wide band of threadlock GM P/N 12345493 (Canadian P/N 10953488), or equivalent to the threads of the exhaust manifold bolts.
4. Install a NEW catalytic converter seal to the catalytic converter.
5. Position the NEW exhaust manifold gasket and exhaust manifold to the cylinder head.
6. Ensure that the exhaust manifold is seated to the catalytic converter.
7. Install the exhaust manifold bolts. Tighten Tighten the bolts a first pass to 15 (11 lb ft). Tighten the exhaust manifold bolts beginning with the center 2 bolts. Alternate from side-to-side, and work toward the outside bolts. Tighten the bolts a final pass to 20 (18 lb ft). Tighten the exhaust manifold bolts beginning with the center 2 bolts. Alternate from side-to-side, and work toward the outside bolts.
8. Using a flat punch, bend the gasket tab at the rear of the gasket around the cylinder head edge.
9. Position and align the marks on the upper intermediate steering shaft and the steering column.
10. Install the upper intermediate steering shaft (3) to the steering column.
11. Install the steering shaft coupling bolt (2) and nut (1) to the upper intermediate steering shaft. Tighten Tighten the bolt/nut to 50 (37 lb ft).
12. Install the spark plug wires to the spark plugs.
13. Install the spark plug wires to the ignition coils.
14. Inspect the spark plug wires for proper installation. Push sideways on each boot in order to inspect the seating. Reinstall any loose boot.
15. Fully raise and support the vehicle.
16. Install the catalytic converter to exhaust manifold nuts. (1500 series shown, 2500 series similar). Tighten Tighten the nuts to 50 (37 lb ft).
17. Partially lower the vehicle.
18. Install the left wheelhouse liner. Refer to «Front Wheelhouse Liner Replacement - Left Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Left Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
19. Remove the J 42640 steering column anti-rotation pin from the steering column lower access hole.

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
2. Remove the catalytic converter to exhaust manifold nuts (1).
3. Lower the vehicle.
4. Remove the exhaust manifold heat shield bolts and shield.
5. Remove the spark plugs. Refer to «Spark Plug Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-43l-repair-instructions) .
6. Reposition the spark plug wires out of the way, if necessary.
7. Remove the exhaust manifold bolts and stud.
8. Remove the exhaust manifold and gaskets (1). Discard the gaskets.
9. Remove the exhaust manifold to catalytic converter seal (2). Discard the seal.

1. Install a NEW exhaust manifold to catalytic converter seal (2) into the relief in the catalytic converter.
2. Place the exhaust manifold into position and install the manifold studs to the catalytic converter.
3. Place the NEW exhaust manifold gaskets (1) between the manifold and the cylinder head.
4. Install the exhaust manifold bolts and stud. Tighten Tighten the bolts/stud to 30 N.m (22 lb ft).
5. Install the spark plugs. Refer to «Spark Plug Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-43l-repair-instructions) .
6. Position the exhaust manifold heat shield to the manifold and install the bolts. Tighten Tighten the bolts to 9 N.m (80 lb in).
7. Raise and support the vehicle.
8. Install the catalytic converter to exhaust manifold nuts (1). Tighten Tighten the nuts to 50 N.m (37 lb ft).
9. Lower the vehicle.

1. Remove the positive crankcase ventilation pipe. Refer to «Positive Crankcase Ventilation Hose/Pipe/Tube Replacement (Regulator Valve to Separator)»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-repair-instructions-on-vehicle) .
2. Remove the left wheelhouse liner. Refer to «Front Wheelhouse Liner Replacement - Left Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Left Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
3. Perform the following steps working through the wheelhouse opening.
4. Remove the steering coupling nut (1) and bolt (2) at the upper intermediate steering shaft.
5. Separate the steering shaft coupling from the intermediate shaft.
6. Remove the left exhaust manifold outlet pipe to the exhaust manifold bolts (1).
7. Discard the gasket (2).
8. Remove the exhaust manifold heat shield bolts (1) and shield (2).
9. Remove the exhaust manifold bolts and nuts in the sequence shown.
10. Remove the exhaust manifold and gasket. Discard the gasket.

1. Install the NEW exhaust manifold gasket onto the manifold studs.
2. Position a NEW exhaust manifold outlet pipe gasket (1) between the exhaust manifold and the exhaust manifold outlet pipe. Align the tab (2) on the gasket to face outward.
3. Install the exhaust manifold onto the studs.
4. Install and tighten the exhaust manifold bolts and nuts in the sequence shown to 57 N.m (42 lb ft).
5. Tighten the 4 center bolts/nuts an additional pass to 57 N.m (42 lb ft)
6. Install and tighten the exhaust pipe to exhaust manifold bolts in the sequence shown (1, 2, and 3) to 53 N.m (39 lb ft).
7. Position the exhaust manifold heat shield (2) to the manifold and install the bolts (1) and tighten to 10 N.m (89 lb in).
8. Install the steering shaft coupling to the intermediate shaft.
9. Install the steering shaft coupling nut (1) and bolt (2) at the steering shaft coupling and tighten to 50 N.m (37 lb in).
10. Install the left wheelhouse liner. Refer to «Front Wheelhouse Liner Replacement - Left Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Left Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
11. Install the positive crankcase ventilation pipe. Refer to «Positive Crankcase Ventilation Hose/Pipe/Tube Replacement (Regulator Valve to Separator)»(/gmc/sierra-2500/2012-2012/remont/mechanical/#engine-mechanical-66l-lgh-lml-repair-instructions-on-vehicle) .
12. Lower the vehicle.

1. Remove the heated oxygen sensor (HO2S). Refer to «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) .
2. Fully raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
3. Remove the catalytic converter to exhaust manifold nuts, 1500 series shown, 2500 series similar.
4. Remove the right wheelhouse liner. Refer to «Front Wheelhouse Liner Replacement - Right Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Right Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
5. Remove the spark plug wires (1) from the spark plugs. Twist the spark plug wire boot a 1/2 turn. Pull only on the boot in order to remove the wire from the spark plug.
6. Remove the spark plug wires from the ignition coils. Twist the spark plug wire boot a 1/2 turn. Pull only on the boot in order to remove the wire from the ignition coil.
7. Remove the oil level indicator tube bolt (419).
8. Remove the oil level indicator tube (420) from the engine block.
9. Remove the exhaust manifold bolts and exhaust manifold.
10. Remove and discard the exhaust manifold gasket.
11. Remove and discard the exhaust manifold seal.
12. If replacing the exhaust manifold, remove the exhaust manifold heat shield bolts, and shield from the exhaust manifold.

Note. Tighten the exhaust manifold bolts as specified in the service procedure. Improperly installed and/or leaking exhaust manifold gaskets may affect vehicle emissions and/or On-Board Diagnostics (OBD) II system performance. The cylinder head exhaust manifold bolt hole threads must be clean and free of debris or threadlocking material. Do not apply sealant to the first 3 threads of the bolt.

1. If the exhaust manifold was replaced, position and install the exhaust manifold heat shield, and bolts to the exhaust manifold. Tighten Tighten the bolts to 9 N.m (80 lb in).
2. Clean the threads of the exhaust manifold bolts.
3. Apply a 5 mm (0.2 in) wide band of threadlock GM P/N 12345493 (Canadian P/N 10953488), or equivalent to the threads of the exhaust manifold bolts.
4. Install a NEW catalytic converter seal to the exhaust manifold.
5. Position the NEW exhaust manifold gasket and exhaust manifold to the cylinder head.
6. Ensure that the catalytic converter seal is seated to the catalytic converter.
7. Install the exhaust manifold bolts. Tighten Tighten the bolts a first pass to 15 N.m (11 lb ft). Tighten the exhaust manifold bolts beginning with the center 2 bolts. Alternate from side-to-side, and work toward the outside bolts. Tighten the bolts a final pass to 20 N.m (18 lb ft). Tighten the exhaust manifold bolts beginning with the center 2 bolts. Alternate from side-to-side, and work toward the outside bolts.
8. Using a flat punch, bend the gasket tab at the rear of the gasket around the cylinder head edge.
9. Inspect the O-ring seal (421) for cuts or damage, replace as necessary.
10. Lubricate the O-ring seal (421) with clean engine oil.
11. Install the oil level indicator tube (420) to the engine block.
12. Install the oil level indicator tube bolt (419). Tighten Tighten the bolt 25 N.m (18 lb ft).
13. Install the spark plug wires (1) to the spark plugs.
14. Install the spark plug wires to the ignition coils.
15. Inspect the spark plug wires for proper installation. Push sideways on each boot in order to inspect the seating. Reinstall any loose boot.
16. Install the right wheelhouse liner. Refer to «Front Wheelhouse Liner Replacement - Right Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Right Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
17. Fully raise and support the vehicle.
18. Install the catalytic converter to exhaust manifold nuts, 1500 series shown, 2500 series similar. Tighten Tighten the nuts to 50 N.m (37 lb ft). Partially lower the vehicle in order to work through the wheel opening. Install the HO2S. Refer to «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) .

1. Remove the heated oxygen sensor (HO2S). Refer to «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-43l-repair-instructions) .
2. Remove the catalytic converter to exhaust manifold nuts (1).
3. Lower the vehicle.
4. Remove the exhaust manifold heat shield bolts and shield.
5. Remove the spark plugs. Refer to «Spark Plug Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-43l-repair-instructions) .
6. Reposition the spark plug wires out of the way, if necessary.
7. Remove the exhaust manifold bolts.
8. Remove the exhaust manifold and gaskets (1). Discard the gaskets.
9. Remove the exhaust manifold to catalytic converter seal (2). Discard the seal.

1. Install a NEW exhaust manifold to catalytic converter seal (2) into the exhaust manifold.
2. Place the exhaust manifold into position and install the manifold studs to the catalytic converter.
3. Place the NEW exhaust manifold gaskets (1) between the manifold and the cylinder head.
4. Install the exhaust manifold bolts and stud. Tighten Tighten the bolts/stud to 30 N.m (22 lb ft).
5. Install the spark plugs. Refer to «Spark Plug Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-43l-repair-instructions) .
6. Position the exhaust manifold heat shield to the manifold and install the bolts. Tighten Tighten the bolts to 9 N.m (80 lb in).
7. Raise and support the vehicle.
8. Install the catalytic converter to exhaust manifold nuts (1). Tighten Tighten the nuts to 50 N.m (37 lb ft).
9. Lower the vehicle.

1. Remove the wheelhouse liner. Refer to «Front Wheelhouse Liner Replacement - Right Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Right Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
2. Disconnect the oxygen sensor.
3. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
4. Remove the catalytic converter. Refer to «Catalytic Converter Replacement (Gen IV Engines with Exhaust Clamp)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (LGH /LML)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with E63)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with ZW9)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with Exhaust Flange)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
5. Perform the following steps working through the wheelhouse opening, remove the exhaust pipe to turbocharger exhaust pipe bracket bolt (1).
6. Loosen the turbocharger exhaust pipe clamp nut (1).
7. Remove the turbocharger exhaust pipe (1) from the engine compartment.
8. Remove the exhaust manifold to turbocharger exhaust pipe bolts (1).
9. Discard the exhaust gasket.
10. Remove the exhaust manifold heat shield bolts (1) and shield.
11. Remove the exhaust manifold bolts and nuts in the proper sequence.
12. Remove the exhaust manifold nuts (1) and bolts (2).
13. Discard the gasket (3) and remove the exhaust manifold (4).

1. Install a NEW exhaust manifold gasket (3) onto the studs.
2. Install the exhaust manifold onto the studs.
3. Install and tighten the exhaust manifold bolts and nuts in the sequence shown and tighten to 57 N.m (42 lb ft).
4. Tighten the 4 center bolts/nuts an additional pass to 57 N.m (42 lb ft).
5. Position the turbocharger exhaust manifold heat shield (2) to the manifold and install the exhaust manifold heat shield bolts (1). Tighten to 10 N.m (89 lb in).
6. Install a NEW gasket (1) to the exhaust manifold outlet pipe with the tabs (2) facing downward.
7. Tighten the exhaust manifold outlet pipe to exhaust manifold bolts in the sequence shown to 50 N.m (37 lb ft).
8. Install the turbocharger exhaust pipe (1) to the turbocharger and exhaust pipe bracket.
9. Tighten turbocharger exhaust pipe bracket bolt (1) to 34 N.m (25 lb ft).
10. Install the catalytic converter to the turbocharger exhaust pipe. Refer to «Catalytic Converter Replacement (Gen IV Engines with Exhaust Clamp)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (LGH /LML)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with E63)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with ZW9)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with Exhaust Flange)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
11. Install the wheelhouse liner. Refer to «Front Wheelhouse Liner Replacement - Right Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Right Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
12. Lower the vehicle.

1. Remove the turbocharger upper heat shield bolts and shield.
2. Loosen the turbocharger exhaust pipe to turbocharger clamp bolt (1).
3. Remove the nitrogen oxide position 1 - sensor. Refer to «Nitrogen Oxide Sensor Replacement - Position 1»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
4. Remove the exhaust temperature sensor. Refer to «Exhaust Temperature Sensor Replacement - Position 1»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
5. Remove the indirect fuel injector. Refer to «Indirect Fuel Injector Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__indirect-fuel-injector-replacement) .
6. Remove the transmission. Refer to «Transmission Replacement»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-allison-repair-instructions-on-vehicle__transmission-replacement) .
7. Remove the catalytic converter. Refer to «Catalytic Converter Replacement (Gen IV Engines with Exhaust Clamp)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (LGH /LML)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with E63)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with ZW9)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with Exhaust Flange)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
8. Remove the turbocharger exhaust pipe to bracket bolt (1).
9. Remove the turbocharger exhaust pipe (1).
10. If replacing the turbocharger exhaust pipe, transfer the exhaust heat shield.

1. Install the turbocharger exhaust pipe (1) into the turbocharger and position the pipe onto the exhaust manifold bracket.
2. Loosely install the turbocharger exhaust pipe to bracket bolt (1).
3. Tighten the turbocharger exhaust pipe to turbocharger clamp bolt (1). Tighten Tighten the bolt to 10 (89 lb in).
4. Install the indirect fuel injector. Refer to «Indirect Fuel Injector Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__indirect-fuel-injector-replacement) .
5. Install the catalytic converter. Refer to «Catalytic Converter Replacement (Gen IV Engines with Exhaust Clamp)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (LGH /LML)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with E63)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with ZW9)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with Exhaust Flange)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
6. Tighten the turbocharger exhaust pipe to bracket bolt (1). Tighten Tighten the bolt to 34 (25 lb ft).
7. Install the turbocharger upper heat shield and bolts. Tighten Tighten the bolts to 10 (89 lb in).
8. Install the exhaust temperature sensor. Refer to «Exhaust Temperature Sensor Replacement - Position 1»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
9. Install the nitrogen oxide position 1 - sensor. Refer to «Nitrogen Oxide Sensor Replacement - Position 1»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions) .
10. Install the transmission. Refer to «Transmission Replacement»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-allison-repair-instructions-on-vehicle__transmission-replacement) .
11. Start the engine and check for exhaust leaks.

1. Remove the heated oxygen sensor (HO2S). Refer to «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) .
2. Support the transmission with a suitable transmission jack.
3. Remove the transmission support crossmember. Refer to «Transmission Support Crossmember Replacement (4WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody__transmission-support-crossmember-replacement-4wd-25003500) , «Transmission Support Crossmember Replacement (4WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody)
4. Remove the exhaust muffler to exhaust manifold pipe nuts (1).
5. Replace the exhaust gasket (2).
6. Remove the exhaust manifold pipe to exhaust manifold nuts (1) and replace the seal (2) with a NEW one.
7. Using the transmission jack, lower the transmission slightly.
8. Separate the exhaust manifold pipe rod (1) from the exhaust isolator bracket (2).

1. Install a NEW exhaust manifold pipe gasket onto the muffler studs.
2. Install the exhaust manifold pipe hanger rod (1) into the exhaust isolator (2).
3. Install any necessary exhaust muffler insulators that were separated from the muffler.
4. Using the transmission jack, raise the transmission slightly.
5. Install the exhaust manifold pipe (3) with the exhaust manifold nuts 1) and tighten to 50 N.m (37 lb ft).
6. Install the exhaust muffler to exhaust manifold pipe nuts (1) and tighten to 45 N.m (33 lb ft).
7. Install the transmission support crossmember. Refer to «Transmission Support Crossmember Replacement (4WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody__transmission-support-crossmember-replacement-4wd-25003500) , «Transmission Support Crossmember Replacement (4WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody)
8. Remove the support from the transmission.
9. Install the HO2S. Refer to «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) .
10. Start the engine and check the front exhaust system for leaks.

1. Remove the transmission. Refer to «Transmission Replacement»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-allison-repair-instructions-on-vehicle__transmission-replacement) .
2. Remove the turbocharger exhaust pipe. Refer to «Turbocharger Exhaust Pipe Replacement»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
3. Remove the EGR cooling feed pipe. Refer to «Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (Cooler to Cooler Hose-LGH)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) , «Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (Cooler to Cooler Hose-LML)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) , «Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (EGR Bypass Pipe-LML)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) , «Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (Manifold Feed Pipe to Cooler Hose-LML)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) , «Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (EGR Manifold Return Hose-LGH, LML)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) , «Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (Manifold Feed Hose to Cooler-LML)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) , «Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (Manifold Feed Pipe/Hose to Cooler-LGH)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Remove the right exhaust manifold outlet pipe heat shield. Refer to «Exhaust Pipe Heat Shield Replacement (Exhaust Manifold Outlet Pipe-Left)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Exhaust Pipe Heat Shield Replacement (Turbocharger Exhaust Pipe)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Exhaust Pipe Heat Shield Replacement (Exhaust Manifold Outlet Pipe-Right)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
5. Remove the exhaust pipe bolts in the proper sequence.
6. Remove the exhaust manifold outlet pipe (8), bracket (4) and gaskets (2, 3, 7). Discard the gaskets.

1. Position the exhaust manifold outlet pipe (8) with a NEW gasket (7) to the turbocharger.
2. Loosely install the exhaust manifold outlet pipe to the turbocharger bolts (6).
3. Install a NEW gasket (2) to the EGR cooler bypass valve with the bolts (1)
4. Loosely install the exhaust manifold outlet pipe bolts (1) to the EGR cooler bypass valve.
5. Position the exhaust manifold outlet pipe with a NEW gasket (3) to the right exhaust manifold. Align the tabs on the gasket to face downward.
6. Loosely install the exhaust manifold outlet pipe and bracket (4) to the right exhaust manifold with bolts (5).
7. Tighten the exhaust manifold outlet pipe bolts in the sequence shown to : To EGR (1, 2, 3, 4) 25 N.m (18 lb ft). To Manifold (5, 6, 7) 53 N.m (39 lb ft). To Turbocharger (8, 9, 10) 25 N.m (18 lb ft).
8. Install the right exhaust manifold outlet pipe heat shield. Refer to «Exhaust Pipe Heat Shield Replacement (Exhaust Manifold Outlet Pipe-Left)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Exhaust Pipe Heat Shield Replacement (Turbocharger Exhaust Pipe)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Exhaust Pipe Heat Shield Replacement (Exhaust Manifold Outlet Pipe-Right)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
9. Install the EGR cooling feed pipe. Refer to «Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (Cooler to Cooler Hose-LGH)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) , «Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (Cooler to Cooler Hose-LML)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) , «Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (EGR Bypass Pipe-LML)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) , «Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (Manifold Feed Pipe to Cooler Hose-LML)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) , «Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (EGR Manifold Return Hose-LGH, LML)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) , «Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (Manifold Feed Hose to Cooler-LML)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) , «Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (Manifold Feed Pipe/Hose to Cooler-LGH)»(/gmc/sierra-2500/2012-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
10. Install the turbocharger exhaust pipe. Refer to «Turbocharger Exhaust Pipe Replacement»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
11. Install the transmission. Refer to «Transmission Replacement»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-allison-repair-instructions-on-vehicle__transmission-replacement) .

1. Remove the turbocharger exhaust pipe. Refer to «Turbocharger Exhaust Pipe Replacement»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
2. Remove the exhaust manifold outlet pipe heat shield. Refer to «Exhaust Pipe Heat Shield Replacement (Exhaust Manifold Outlet Pipe-Left)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Exhaust Pipe Heat Shield Replacement (Turbocharger Exhaust Pipe)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Exhaust Pipe Heat Shield Replacement (Exhaust Manifold Outlet Pipe-Right)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
3. Remove the exhaust manifold outlet pipe bolts in the proper sequence.
4. Remove the exhaust manifold outlet pipe (3).

1. Install a NEW gasket to the EGR cooler with the tab (3) facing upward.
2. Install a NEW gasket to the turbocharger with the tab (2) facing inward.
3. Install a NEW gasket to the right exhaust manifold with the tabs (1) facing downward.
4. Position the exhaust manifold outlet pipe (8).
5. Loosely tighten the exhaust manifold outlet pipe to the turbocharger with the bolts (4).
6. Loosely tighten the bolts (2) and nuts (1) to the EGR valve cooler.
7. Loosely tighten the exhaust manifold outlet pipe bolts (3) and turbocharger bolts (4).
8. Tighten the exhaust manifold outlet pipe bolts and nuts in the sequence shown to : To EGR (1, 2, 3, 4) 25 N.m (18 lb ft). To Manifold (5, 6, 7) 53 N.m (39 lb ft). To Turbocharger (8, 9, 10) 25 N.m (18 lb ft).
9. Install the exhaust manifold outlet pipe heat shield. Refer to «Exhaust Pipe Heat Shield Replacement (Exhaust Manifold Outlet Pipe-Left)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Exhaust Pipe Heat Shield Replacement (Turbocharger Exhaust Pipe)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Exhaust Pipe Heat Shield Replacement (Exhaust Manifold Outlet Pipe-Right)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
10. Install the turbocharger exhaust pipe. Refer to «Turbocharger Exhaust Pipe Replacement»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
11. Start the engine and check for exhaust leaks.

1. Remove the transmission. Refer to «Transmission Replacement»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-allison-repair-instructions-on-vehicle__transmission-replacement) .
2. Remove the turbocharger exhaust pipe. Refer to «Turbocharger Exhaust Pipe Replacement»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
3. Remove the left exhaust manifold outlet pipe heat shield. Refer to «Exhaust Pipe Heat Shield Replacement (Exhaust Manifold Outlet Pipe-Left)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Exhaust Pipe Heat Shield Replacement (Turbocharger Exhaust Pipe)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Exhaust Pipe Heat Shield Replacement (Exhaust Manifold Outlet Pipe-Right)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
4. Remove the exhaust manifold outlet pipe bolts in the proper sequence.
5. Remove the exhaust manifold outlet pipe bolts (1) and replace gaskets (2) with NEW gaskets.
6. Remove the exhaust manifold outlet pipe (3).

1. Install a NEW gasket to the left exhaust manifold with the tab (1) facing downward.
2. Install a NEW gasket to the turbocharger with the tab (2) facing inward.
3. Position the exhaust manifold outlet pipe (3). Loosely install the turbocharger and the exhaust manifold bolts (1).
4. Tighten the exhaust manifold outlet pipe bolts in the sequence shown to: To Manifold (1, 2, 3) 53 N.m (39 lb ft). To Turbocharger (4, 5, 6) 25 N.m (18 lb ft).
5. Install the left exhaust manifold outlet pipe heat shield. Refer to «Exhaust Pipe Heat Shield Replacement (Exhaust Manifold Outlet Pipe-Left)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Exhaust Pipe Heat Shield Replacement (Turbocharger Exhaust Pipe)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Exhaust Pipe Heat Shield Replacement (Exhaust Manifold Outlet Pipe-Right)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system)
6. Install the turbocharger exhaust pipe. Refer to «Turbocharger Exhaust Pipe Replacement»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
7. Install the transmission. Refer to «Transmission Replacement»(/gmc/sierra-2500/2012-2012/remont/automatic-trans/#automatic-transmission-allison-repair-instructions-on-vehicle__transmission-replacement)
8. Start the engine and check for exhaust leaks.

1. Remove the left catalytic converter, if required. Refer to «Catalytic Converter Replacement - Left Side (ZW9)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
2. Remove the exhaust manifold pipe, if required. Refer to «Exhaust Manifold Pipe Replacement (ZW9)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
3. Remove and discard the appropriate exhaust seal (1) or gasket (2).

1. Install the NEW appropriate exhaust seal (1) or gasket (2).
2. Install the exhaust manifold pipe, if required. Refer to «Exhaust Manifold Pipe Replacement (ZW9)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
3. Install the left catalytic converter, if required. Refer to «Catalytic Converter Replacement - Left Side (ZW9)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .

Scheme 2

Exhaust Seal Replacement (V6/V8)

Scheme 3

Catalytic Converter Replacement (Gen IV Engines with Exhaust Clamp)

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
2. Remove the transmission crossmember. Refer to «Transmission Support Crossmember Replacement (4WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody__transmission-support-crossmember-replacement-4wd-25003500) , «Transmission Support Crossmember Replacement (4WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
3. Disconnect the engine harness connector (1), the emission reduction fluid injector connector (2), and the temperature sensor from the catalytic converter.
4. Remove the catalytic converter to diesel particulate filter nuts (3).
5. Loosen the turbocharger exhaust pipe-to-catalytic converter clamp (1).
6. Remove the exhaust hanger bracket bolt (1) and bracket stud (2).
7. With the catalytic converter exhaust isolator attached, lower the catalytic converter with the exhaust bracket (3).
8. If replacing catalytic converter, transfer the exhaust isolator and the exhaust temperature sensor.

1. If replacing the catalytic converter, apply water based lubricant to the exhaust isolator for ease of installation.
2. Position the catalytic converter to the turbocharger exhaust outlet pipe.
3. Position the catalytic converter with the exhaust bracket (3) to the engine.
4. Tighten the bolt (1) and stud (2) to 25 N.m (18 lb ft).
5. Install the catalytic converter to particulate filter nuts (3) until snug.
6. Slide the exhaust pipe clamp (1) down and around the pipe connection.
7. Tighten the exhaust pipe clamp to 14 N.m (124 lb in).
8. Install a NEW catalytic converter to diesel particulate filter gasket (2).
9. Install the catalytic converter to particulate filter nuts (1) until snug.
10. Tighten the catalytic to diesel particulate filter nuts (1) to 45 N.m (33 lb ft).
11. Connect the emission reduction fluid injector connector (2) and the engine harness connector (1).
12. Install the transmission crossmember. Refer to «Transmission Support Crossmember Replacement (4WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody__transmission-support-crossmember-replacement-4wd-25003500) , «Transmission Support Crossmember Replacement (4WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
13. Lower the vehicle.
14. Start the engine and check for leaks.
15. Perform the scan tool Diesel Particulate Filter (DPF) Regeneration Enable. Refer to «Diesel Particulate Filter (DPF) Regeneration Enable»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-66l-lgh-lml-repair-instructions__diesel-particulate-filter-dpf-regeneration-enable) .

1. Disconnect the heated oxygen sensor (HO2S). Refer to the following: «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) «Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions)
2. Support the transmission with a suitable transmission jack.
3. Remove the transmission support crossmember. Refer to «Transmission Support Crossmember Replacement (4WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody__transmission-support-crossmember-replacement-4wd-25003500) , «Transmission Support Crossmember Replacement (4WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody)
4. Remove the exhaust muffler to exhaust manifold pipe nuts (1).
5. Remove the exhaust manifold pipe to exhaust manifold nuts (1) and replace the seal (2) with a NEW one.
6. Remove the right catalytic converter (3) from the exhaust manifold studs with the nuts (1).
7. Separate the catalytic converter hanger rod (1) from the exhaust isolator.
8. With the aid of an assistant, lower the catalytic converter (1) from the vehicle.
9. If replacing the catalytic converter, transfer the oxygen sensors.

1. Install the catalytic converter hanger rod (1) into the exhaust isolator.
2. Install a NEW seal (2) to the left manifold exhaust pipe. Tighten the nuts (1) to 50 N.m (37 lb ft)
3. Inspect the seal (2) and replace if worn or damaged.
4. Install the right catalytic converter to the exhaust manifold with nuts (1) and tighten to 50 N.m (37 lb ft).
5. Install the exhaust muffler to catalytic converter (2) with nuts (1) and tighten to 45 N.m (33 lb ft).
6. Install the transmission support crossmember. Refer to «Transmission Support Crossmember Replacement (4WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody__transmission-support-crossmember-replacement-4wd-25003500) , «Transmission Support Crossmember Replacement (4WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody)
7. Remove the support from the transmission.
8. Connect the HO2S sensors. Refer to the following: «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) «Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions)
9. Start the engine and check the front exhaust system for leaks.

1. Disconnect the heated oxygen sensor (HO2S). Refer to the following: «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) «Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions)
2. Support the transmission with a suitable transmission jack.
3. Remove the transmission support crossmember. Refer to «Transmission Support Crossmember Replacement (4WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody__transmission-support-crossmember-replacement-4wd-25003500) , «Transmission Support Crossmember Replacement (4WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody)
4. Remove the exhaust muffler nuts (1) from the catalytic converter (3).
5. Remove the exhaust muffler isolator rod (2) from the exhaust isolator.
6. Remove the exhaust manifold pipe to exhaust manifold nuts (1) and discard the seal (2).
7. Remove the right catalytic converter (3) and seal (2), from the exhaust manifold with the bolts (1).
8. Separate the catalytic converter hanger rod (1) from the exhaust isolator.
9. With the aid of an assistant, lower the catalytic converter (2) from the vehicle.
10. If replacing the catalytic converter, transfer the oxygen sensors.

1. Install the catalytic converter hanger rod (1) into the exhaust isolator.
2. Install a NEW seal (2) to the left manifold exhaust pipe. Tighten the nuts (1) to 50 N.m (37 lb ft).
3. Inspect the seal (2) and replace if worn or damaged.
4. Install the right catalytic converter to the exhaust manifold with nuts (1) and tighten to 50 N.m (37 lb ft).
5. Instal the exhaust muffler hanger rod (2) into the exhaust isolator.
6. Install the exhaust muffler to catalytic converter (3) with the nuts (1) and tighten to 45 N.m (33 lb ft).
7. Install the transmission support crossmember. Refer to «Transmission Support Crossmember Replacement (4WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody__transmission-support-crossmember-replacement-4wd-25003500) , «Transmission Support Crossmember Replacement (4WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody)
8. Remove the support from the transmission.
9. Connect the HO2S sensors. Refer to the following: «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) «Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions)
10. Start the engine and check the front exhaust system for leaks.

1. Disconnect the heated oxygen sensor (HO2S). Refer to the following: «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) «Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions)
2. Support the transmission with a suitable transmission jack.
3. Remove the transmission support crossmember. Refer to «Transmission Support Crossmember Replacement (4WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody__transmission-support-crossmember-replacement-4wd-25003500) , «Transmission Support Crossmember Replacement (4WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody)
4. Remove the exhaust muffler nuts (1) from the catalytic converter (3).
5. Remove the exhaust muffler isolator rod (2) from the exhaust isolator.
6. Remove the exhaust manifold pipe to exhaust manifold nuts (1) and replace the seal (2) with a NEW one.
7. Remove the right catalytic converter (3) and seal (2), from the exhaust manifold with the bolts (1).
8. Separate the catalytic converter hanger rod (1) from the exhaust isolator.
9. With the aid of an assistant, lower the catalytic converter (2) from the vehicle.
10. If replacing the catalytic converter, transfer the oxygen sensors.

1. Install the catalytic converter hanger rod (1) into the exhaust isolator.
2. Install a NEW seal (2) to the left manifold exhaust pipe. Tighten the nuts (1) to 50 N.m (37 lb ft).
3. Inspect the seal (2) and replace if worn or damaged.
4. Install the right catalytic converter to the exhaust manifold with nuts (1) and tighten to 50 N.m (37 lb ft).
5. Instal the exhaust muffler hanger rod (2) into the exhaust isolator.
6. Install the exhaust muffler to catalytic converter (3) with the nuts (1) and tighten to 45 N.m (33 lb ft).
7. Install the transmission support crossmember. Refer to «Transmission Support Crossmember Replacement (4WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody__transmission-support-crossmember-replacement-4wd-25003500) , «Transmission Support Crossmember Replacement (4WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody)
8. Remove the support from the transmission.
9. Connect the HO2S sensors. Refer to the following: «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) «Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions)
10. Start the engine and check the front exhaust system for leaks.

1. Disconnect the heated oxygen sensor (HO2S). Refer to the following: «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions)
2. Support the transmission with a suitable transmission jack.
3. Remove the transmission support crossmember. Refer to «Transmission Support Crossmember Replacement (4WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody__transmission-support-crossmember-replacement-4wd-25003500) , «Transmission Support Crossmember Replacement (4WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody)
4. Remove the exhaust muffler clamp nut (3).
5. Remove the exhaust manifold pipe to exhaust manifold nuts (1) and discard the seal (2).
6. Separate the catalytic converter hanger rod (1) from the exhaust isolator.
7. With the aid of an assistant, lower the catalytic converter (2) from the vehicle.
8. If replacing the catalytic converter, transfer the oxygen sensors.

1. Install the catalytic converter hanger rod (1) into the exhaust isolator.
2. Install a NEW seal (2) to the left manifold exhaust pipe. Tighten the nuts (1) to 50 N.m (37 lb ft).
3. Install the exhaust muffler to catalytic converter (2) with clamp nut (3) and tighten to 28 N.m (21 lb ft).
4. Install the transmission support crossmember. Refer to «Transmission Support Crossmember Replacement (4WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody__transmission-support-crossmember-replacement-4wd-25003500) , «Transmission Support Crossmember Replacement (4WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 1500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Transmission Support Crossmember Replacement (2WD 2500/3500 Series)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody)
5. Remove the support from the transmission.
6. Connect the HO2S sensors. Refer to the following: «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (1500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series - Cab/Chassis)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) , «Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series)»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions)
7. Start the engine and check the front exhaust system for leaks.

Scheme 4

Exhaust Particulate Filter Replacement (03 Series)

Scheme 5

Exhaust Particulate Filter Replacement (53 Series)

Scheme 6

Exhaust Particulate Filter Replacement (43 Series)

1. If equipped with a 6.0L engine, remove the exhaust manifold pipe. Refer to «Exhaust Manifold Pipe Replacement (ZW9)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
2. If equipped with a 6.0L engine, remove the left catalytic converter. Refer to «Catalytic Converter Replacement - Left Side (ZW9)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
3. If equipped with a 6.6L engine, remove the catalytic converter. Refer to «Catalytic Converter Replacement (Gen IV Engines with Exhaust Clamp)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (LGH /LML)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with E63)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with ZW9)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with Exhaust Flange)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
4. If equipped with a 4L80-E automatic transmission, regular production option (RPO) MT1, remove the exhaust pipe hanger bracket bolts and bracket.
5. If equipped with a Allison® automatic transmission, RPO MW7, remove the exhaust pipe hanger bracket bolt/stud and bracket.
6. If equipped with a 6L90-E automatic transmission, RPO MYD, remove the exhaust pipe hanger bracket bolts and bracket.

1. If equipped with a 6L90-E automatic transmission, RPO MYD, install the exhaust pipe hanger bracket and bolts and tighten to 25 N.m (18 lb ft).
2. If equipped with a Allison® automatic transmission, RPO MW7, install the exhaust pipe hanger bracket and bolt/stud and tighten to 25 N.m (18 lb ft).
3. If equipped with a 4L80-E automatic transmission, RPO MT1, install the exhaust pipe hanger bracket and bolts and tighten to 25 N.m (18 lb ft).
4. If equipped with a 6.6L engine, install the catalytic converter. Refer to «Catalytic Converter Replacement (Gen IV Engines with Exhaust Clamp)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (LGH /LML)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with E63)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with ZW9)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with Exhaust Flange)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
5. If equipped with a 6.0L engine, install the left catalytic converter. Refer to «Catalytic Converter Replacement - Left Side (ZW9)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
6. If equipped with a 6.0L engine, install the exhaust manifold pipe. Refer to «Exhaust Manifold Pipe Replacement (ZW9)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .

Scheme 7

Exhaust Hanger Mounting Bracket Replacement (with L96/E63/ZW9)

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
2. Lower the spare tire.
3. Remove the catalytic converter to exhaust muffler nuts.
4. If equipped with a exhaust muffler clamp (Norma), loosen the catalytic to exhaust muffler clamp nut (1).
5. If equipped with a 4.8L engine, perform the following steps, otherwise proceed to step 7.
6. Lubricate the 3 insulators where the muffler assembly hangers are inserted in order to ease removal.
7. With the aid of an assistant, remove the insulators (1, 2) from the front and rear muffler assembly hangers.
8. Remove the insulator (1) from the intermediate muffler assembly hanger and remove the muffler assembly.
9. If equipped with a 5.3L, or a 6.0L engine, lubricate the 3 insulators where the muffler assembly hangers are inserted in order to ease removal.
10. With the aid of an assistant, remove the insulators (1, 2) from the front and rear muffler assembly hangers.
11. Remove the insulators (1) from the intermediate muffler assembly hangers and remove the muffler assembly. Pull the muffler assembly rearward until the flange is able to clear the front frame crossmember, and remove the muffler toward the front of the vehicle.

1. If equipped with a 4.8L engine, perform the following steps, otherwise proceed to step 6.
2. Lubricate the 3 insulators where the muffler assembly hangers are inserted in order to ease installation.
3. With the aid of an assistant, position and install the muffler assembly.
4. Install the insulators (1, 2) to the front and rear muffler assembly hangers.
5. Install the insulator (1) to the intermediate muffler assembly hanger.
6. If equipped with a 5.3L, or a 6.0L engine, lubricate the 3 insulators where the muffler assembly hangers are inserted in order to ease installation.
7. With the aid of an assistant, position and install the muffler assembly.
8. Install the insulators (1, 2) to the front and rear muffler assembly hangers.
9. Install the insulator (1) to the intermediate muffler assembly hanger.
10. Install the catalytic converter to exhaust muffler nuts and tighten to 45 N.m (33 lb ft).
11. For mufflers using an exhaust clamp (Norma), install the catalytic converter to the exhaust muffler and tighten clamp nut (1) to 28 N.m (21 lb ft).
12. Return the spare tire to the original position.
13. Lower the vehicle.

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
2. Remove the spare tire, if necessary.
3. Install adjustable jack stands under the rear axle, if necessary.
4. If equipped with a 8.6 or a 9.5 inch ring gear, remove the rear axle vent hose from the rear axle, if necessary.
5. Remove the vent hose swivel clip from the rear brake crossover pipe, if necessary.
6. If equipped with a 10.5 inch ring gear, remove the rear axle vent hose from the rear axle, if necessary.
7. Remove the vent hose swivel clip from the rear brake crossover pipe, if necessary.
8. Remove the rear shock absorber lower bolts and nuts, if necessary.
9. Lower the rear axle using the adjustable jack stands, if necessary.
10. Remove the catalytic converter to muffler nuts.
11. If equipped with a exhaust muffler clamp (Norma), loosen the catalytic to exhaust muffler clamp nut (1).
12. Lubricate the 5 insulators where the muffler assembly hangers are inserted in order to ease removal.
13. With the aid of an assistant, remove the insulators (1-3) from the front, intermediate and rear muffler assembly hangers.
14. Remove the insulator (1) from the tail pipe hanger and remove the muffler assembly.

1. Lubricate the 5 insulators where the muffler assembly hangers are inserted in order to ease installation.
2. With the aid of an assistant, position and install the muffler assembly.
3. Install the insulator (1) to the rear tail pipe hanger.
4. Install the insulators (1-3) to the front, intermediate, and rear muffler assembly hangers.
5. Install the catalytic converter to muffler nuts and tighten to 45 N.m (33 lb ft).
6. For mufflers using a exhaust muffler clamp (Norma), install the catalytic converter to the exhaust muffler nut (1) and tighten the clamp to 28 N.m (21 lb ft)
7. Raise the rear axle using the adjustable jack stands, if necessary.
8. Install the rear shock absorber lower bolts and nuts, if necessary and tighten to 95 N.m (70 lb ft).
9. If equipped with a 10.5 inch ring gear, install the rear axle vent hose to the rear axle, if necessary.
10. Connect the vent hose swivel clip to the rear brake crossover pipe, if necessary.
11. If equipped with a 8.6 or a 9.5 inch ring gear, install the rear axle vent hose to the rear axle, if necessary.
12. Install the vent hose swivel clip to the rear brake crossover pipe, if necessary.
13. Remove the adjustable jack stands from under the rear axle, if necessary.
14. Install the spare tire, if necessary.
15. Lower the vehicle.

Scheme 8

Exhaust Muffler Replacement (L96 43 Series ZW9)

Scheme 9

Exhaust Muffler Replacement (L96 03 Series ZW9)

Scheme 10

Exhaust Muffler Replacement (L96 310/314 and 03/43 Series ZW9)

Scheme 11

Exhaust Muffler Replacement (L96 53 Series ZW9)

Scheme 12

Exhaust Muffler Replacement (6.0L 03 Series E63)

Scheme 13

Exhaust Muffler Replacement (6.0L 43/53 Series E63)

1. Remove the catalytic converter. Refer to «Catalytic Converter Replacement (Gen IV Engines with Exhaust Clamp)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (LGH /LML)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with E63)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with ZW9)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with Exhaust Flange)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .
2. If vehicle has a regular cab, remove the exhaust heat shield nuts.
3. Remove the exhaust front heat shield (1) and/or the rear exhaust heat shield (2) from the studs.
4. If vehicle has extended cab, remove the exhaust heat shield nuts.
5. Remove the exhaust front heat shield (1) and/or the rear exhaust heat shield (2) from the studs.
6. If vehicle has a crew cab, remove the exhaust heat shield nuts.
7. Remove the exhaust front heat shield (1) and/or the rear exhaust heat shield (2) from the studs.

1. If vehicle has a crew cab, position and install the rear exhaust heat shield (2) and/or the front exhaust heat shield (1) to the underbody studs.
2. Install the exhaust heat shield nuts and tighten to 9 N.m (80 lb in).
3. If vehicle has a extended cab, position and install the rear exhaust heat shield (2) and/or the front exhaust heat shield (1) to the underbody studs.
4. Install the exhaust heat shield nuts and tighten to 9 N.m (80 lb in).
5. If vehicle has a regular cab, position and install the rear exhaust heat shield (2) and/or the front exhaust heat shield (1) to the studs.
6. Install the exhaust heat shield nuts and tighten to 9 N.m (80 lb in).
7. Install the catalytic converter. Refer to «Catalytic Converter Replacement (Gen IV Engines with Exhaust Clamp)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (LGH /LML)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with E63)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with ZW9)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) , «Catalytic Converter Replacement (L96 with Exhaust Flange)»(/gmc/sierra-2500/2012-2012/remont/exhaust/#engine-exhaust-system) .

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/gmc/sierra-2500/2012-2012/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
2. Remove the exhaust heat shield nuts.
3. Remove both wheelhouse panels. Refer to «Front Wheelhouse Liner Replacement - Right Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Right Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , and «Front Wheelhouse Liner Replacement - Left Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Left Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
4. Remove the exhaust heat shield (1, 3) from the dash panel studs.
5. Remove the heat shield (1, 3) through the respective wheelwell.

1. Install the heat shields (1, 3) through the respective wheelwell.
2. Install the exhaust heat shield (1, 3) to the dash panel studs.
3. Install the exhaust heat shield nuts and tighten to 9 N.m (80 lb in).
4. Lower the vehicle.

1. Remove the right wheelhouse liner. Refer to «Front Wheelhouse Liner Replacement - Right Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Right Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
2. Remove the exhaust manifold heat shield bolts and heat shield from the exhaust manifold.

1. Position the exhaust manifold heat shield to the exhaust manifold and install the heat shield bolts. Tighten Tighten the bolts to 9 N.m (80 lb in).
2. Install the right wheelhouse liner. Refer to «Front Wheelhouse Liner Replacement - Right Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Right Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .

1. Remove the spark plug wires. Refer to «Spark Plug Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) .
2. Reposition the spark plug wires out of the way, if necessary.
3. Remove the exhaust manifold heat shield bolts and heat shield from the exhaust manifold.

1. Position the exhaust manifold heat shield to the exhaust manifold and install the heat shield bolts. Tighten Tighten the bolts to 9 N.m (80 lb in).
2. Install the spark plug wires. Refer to «Spark Plug Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) .

Scheme 14

Exhaust Manifold Heat Shield Replacement - Right Side (Diesel)

1. Remove the spark plug wires. Refer to «Spark Plug Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) .
2. Reposition the spark plug wires out of the way, if necessary.
3. Remove the exhaust manifold heat shield bolts and heat shield from the exhaust manifold.

1. Position the exhaust manifold heat shield to the exhaust manifold and install the heat shield bolts. Tighten Tighten the bolts to 9 N.m (80 lb in).
2. Install the spark plug wires. Refer to «Spark Plug Replacement»(/gmc/sierra-2500/2012-2012/remont/testing-diagnostics/#engine-controlsfuel-48l-53l-60l-62l-repair-instructions) .

1. Remove the left wheelhouse liner. Refer to «Front Wheelhouse Liner Replacement - Left Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Left Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .
2. Remove the exhaust manifold heat shield bolts and heat shield from the exhaust manifold.

1. Position the exhaust manifold heat shield to the exhaust manifold and install the heat shield bolts. Tighten Tighten the bolts to 9 N.m (80 lb in).
2. Install the left wheelhouse liner. Refer to «Front Wheelhouse Liner Replacement - Left Side (GMC)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) , «Front Wheelhouse Liner Replacement - Left Side (Chevrolet)»(/gmc/sierra-2500/2012-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) .

Scheme 15

Exhaust Manifold Heat Shield Replacement - Left Side (Diesel)

Scheme 16

Exhaust Pipe Heat Shield Replacement (Exhaust Manifold Outlet Pipe-Left)

Scheme 17

Exhaust Pipe Heat Shield Replacement (Exhaust Manifold Outlet Pipe-Right)

Scheme 18

Exhaust Pipe Heat Shield Replacement (Turbocharger Exhaust Pipe)

Exhaust System Description

The exhaust system carries exhaust gases, treated by the catalytic converter, through the muffler and into a resonator, if applicable where exhaust noise is lessened.

In order to secure the exhaust muffler assembly to the exhaust manifold, a flange and seal-joint coupling is utilized. The exhaust system may utilize a slip-joint coupling design with a clamp and a U-bolt or a flange connection with a gasket.

Exhaust hangers and rubber insulators help to support the weight of the exhaust system along with insulating any exhaust system vibration, rattle, or noise.

Exhaust hangers also space the exhaust system away from the underbody of the vehicle and allows the exhaust system to expand as the exhaust system warms up.

Exhaust heat shields are used to protect the underbody and other components from damage due to the heat from the exhaust system.

The exhaust system may be comprised of the following components

1. Catalytic converter
2. Exhaust hanger
3. Exhaust heat shield
4. Exhaust insulator
5. Exhaust manifold
6. Exhaust muffler
7. Exhaust pipe
8. Exhaust resonator, if equipped
9. Exhaust tail pipe, if equipped

Catalytic Converter

The catalytic converter is an emission control device added to the engine exhaust system in order to reduce hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) pollutants from the exhaust gas.

The catalytic converter is comprised of a ceramic monolith substrate, supported in insulation and housed within a sheet metal shell. The substrate may be washcoated with 3 noble metals

1. Palladium (Pd)
2. Platinum (Pt)
3. Rhodium (Rh)

The catalyst in the converter is not serviceable.

Muffler

The exhaust muffler reduces the noise levels of the engine exhaust by the use of tuning tubes. The tuning tubes create channels inside the exhaust muffler that lower the sound levels created by the combustion of the engine.

Resonator

Some exhaust systems may be equipped with a resonator. The resonator, located either before or after the muffler, allows the use of mufflers with less back pressure. Resonators are used when vehicle characteristics require specific exhaust tuning.

Special Tools

Illustration Tool Number/Description J 35314-A/BT-8515/BT-8515A Exhaust Back Pressure Tester J 38185 Hose Clamp Pliers J 44626 Oxygen Sensor Socket

Scheme 19

See also:
• Strategy Based Diagnosis
• Diesel Particulate Filter (DPF) Service Regeneration
• Heated Oxygen Sensor Replacement - Bank 1 Sensor 1
• Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (2500 Series - Cab/Chassis)
• Front Wheelhouse Liner Replacement - Left Side (GMC)
• Lifting and Jacking the Vehicle
• Fastener Caution
• Positive Crankcase Ventilation Hose/Pipe/Tube Replacement (Regulator Valve to Separator)
• Indirect Fuel Injector Replacement
• Transmission Replacement
• Exhaust Service Warning
• Hot Exhaust System Warning
• Transmission Support Crossmember Replacement (4WD 2500/3500 Series)
• Exhaust Gas Recirculation Coolant Hoses/Pipes Replacement (Cooler to Cooler Hose-LGH)
• Diesel Particulate Filter (DPF) Regeneration Enable
• Shock Absorber Replacement (2500, 3500)
• Rear Axle Replacement (15 Series With Drum Brakes)
• Transmission Heat Shield Replacement
• Exhaust System Description
• Restricted Exhaust
• Exhaust Leakage
• Exhaust Noise
• Symptoms - Engine Exhaust
• Fastener Tightening Specifications
• Exhaust Manifold Replacement - Left Side (V8)