Engine Speed (RPM) Sensor G28 , Checking Audi TT 8N

Note. Use only gold-plated terminals when servicing terminals in the electrical harness connector of the Engine Speed (RPM) Sensor G28.

Special tools, testers and auxiliary items required

1. Multimeter.
2. Wiring diagram.

Test requirements

1. The Motronic Engine Control Module (ECM) J220 fuses OK.
2. Battery voltage at least 12.5 volts.
3. All electrical consumers such as, lights and rear window defroster, switched off.

1. Vehicles with automatic transmission, shift selector lever into position "P" or "N".
2. A/C switched off.
3. Ground (GND) connections between engine/transmission/chassis OK.
4. Ignition switched off.

Test procedure

1. Perform a preliminary check to verify the customers complaint. Refer to --> «General Diagnosis»(ref-276276-S40851803372008010300000) .

Start diagnosis

The Engine Speed (RPM) Sensor G28 detects RPM and reference marks. Without an engine speed signal, the engine will not start. If the engine speed signal fails while the engine is running, the engine will stop immediately.

Function test

1. Connect the scan tool.
2. Switch the ignition on.
3. Using the scan tool, check the engine speed

1. End diagnosis and switch ignition off.

If the specified value was not obtained

Checking internal resistance

Scheme 36

1. Disconnect the Engine Speed (RPM) Sensor G28 electrical harness connector - 1 -.

Scheme 37

1. Using a multimeter , check the Engine Speed (RPM) Sensor G28 terminals 2 to 3 for resistance.

Specified value: 0.7 to 1000 kOhm

1. Check the Engine Speed (RPM) Sensor G28 terminals 1 to 2 and 1 to 3 for short circuits.

Specified value: infinity (infinity)

If any of the specified values are not obtained

1. Replace the Engine Speed (RPM) Sensor G28. Refer to --> «13 ENGINE - CRANKSHAFT, CYLINDER BLOCK»(ref-276269-S29453351912008010300000)

If the specified values are obtained

Checking wiring

If the manufacturers test box is being used. Perform the following step.

1. Install the Test box VAG1598/31. Refer to --> «24 MULTIPORT FUEL INJECTION (MFI)»(ref-276275-S13244009452008010300000)

If the manufacturers test box is not being used. Perform the following step.

1. Remove the Motronic Engine Control Module (ECM) J220. Refer to --> «Motronic Engine Control Module (ECM) J220, Replacing»(ref-276276-S39982482672008010300000) .

1. Using a Multimeter , check the Engine Speed (RPM) Sensor G28 electrical harness connector terminals to the Motronic Engine Control Module (ECM) J220 electrical harness connector terminals for resistance.

Specified value: 1.5 ohms Max.

If the specification was not obtained

1. Check the wiring for an open circuit, short circuit to each other, Battery (+), and Ground (GND).
2. Check the electrical harness connector for damage, corrosion, loose or broken terminals.
3. If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring

1. Remove the Engine Speed (RPM) Sensor G28 and check the sensor wheel for proper seating, damage and run-out. Refer to --> «13 ENGINE - CRANKSHAFT, CYLINDER BLOCK»(ref-276269-S29453351912008010300000)

If the sensor wheel is OK

1. Erase the DTC memory. Refer to --> «Diagnostic Mode 04: Reset/Delete Diagnostic Data»(ref-276276-S31279847122008010300000) .
2. Perform a road test to verify repair.

If the DTC does not return

Repair complete, Generate readiness code. Refer to --> Readiness Code .

1. End diagnosis.

If the DTC does return and no malfunction is detected in the wiring and the voltage supply was not OK

1. Replace the Motronic Engine Control Module (ECM) J220. Refer to --> «Motronic Engine Control Module (ECM) J220, Replacing»(ref-276276-S39982482672008010300000) .
2. Assembly is performed in the reverse of the removal.

Final procedures

After repair work, the following work steps must be performed in the following sequence

1. Check the DTC memory.
2. If necessary, erase the DTC memory. Refer to «Diagnostic Mode 04: Reset/Delete Diagnostic Data»(ref-276276-S31279847122008010300000) .
3. If the DTC memory was erased, generate readiness code. Refer to «Readiness Code»(ref-276276-S05799074302008010300000) .

End of diagnosis