Emission Control Description & Operation - Diesel: Overview Volkswagen Beetle A4

EGR System, Overview

Exhaust gas is removed from the exhaust manifold -1- and enters the intake manifold -3- via the EGR vacuum regulator solenoid valve -2-.

Actuation is by vacuum from vacuum pump -4- while control is provided by the automatic glow time control module -J179- (item -8-) via the two-way valve for EGR -N161- (item -5-).

When engine is cold, under full load, certain RPM ranges and at altitudes above 3300 feet, the EGR is switched off as follows

1. At temperatures below +50 °C (122 °F) and engine is cold, EGR is switched off via sensor for engine temperature -G27- (item -6-).
2. The EGR part throttle switch - F166- (item -7-) for EGR (on injection pump) ensures that exhaust gas is only recirculated during part throttle operation.
3. Engine speed limiting is affected by automatic glow time control module -J179- (item -8-) and Generator terminal "W" (item -9-). When engine speed exceeds 1200 RPM, EGR is interrupted for 2 seconds. When engine speed exceeds 3200 RPM, EGR is switched off.
4. At altitudes over approx. 3300 feet, EGR is switched off by altitude correction features in automatic glow time control module -8-.

Exhaust Gas Recirculation (EGR) System Components (Engine Code AAZ). Scheme 34

Note. Functional control of Exhaust Gas Recirculation (EGR) system is performed by Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) -J248- via the EGR vacuum regulator solenoid valve -N18-. Check EGR vacuum regulator solenoid valve - N18- using Output Diagnostic Test Mode (DTM). The cone shaped plunger in the mechanical EGR valve enables various cross sectional openings at different plunger heights. Every conceivable valve position is possible via pulsed control. Always replace self-locking nuts.

EGR System Components (Engine Code 1Z). Scheme 35

Vacuum Hose Connections (Engine Code 1Z). Scheme 36

Exhaust Gas Recirculation (EGR) System Components (Engine Code AHU). Scheme 37

Exhaust Gas Recirculation (EGR) System, Overview

Note. The Exhaust Gas Recirculation (EGR) system is activated by the Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) J248 via the EGR Potentiometer G212 to the EGR valve. The cone-shaped plunger in the mechanical EGR valve ensures that various cross sectional openings are possible at different plunger heights. Every possible valve position is provided via pulsed control. Replace self-locking nuts.

Exhaust Gas Recirculation System Components, Assembly Overview

1 - Bracket

1. For bypass flap

2 - 22 Nm

3 - 5 Nm

4 - Intake manifold

1. With EGR vacuum regulator valve -N121- and Motor for intake flap -V157

5 - O-ring

1. Replace

6 - EGR vacuum regulator valve -N121

7 - 10 Nm

8 - Seal

1. Replace

9 - Connecting pipe

10 - Cooler

11 - Exhaust manifold

12 - Seal

1. Replace

13 - Connecting pipe

14 - Seal

1. Replace

15 - Bypass flap

1. Vacuum hose connection diagram. Refer to «Vacuum hose connection diagram»(ref-338222-S36006057192009081800000)

Scheme 38

Exhaust Gas Recirculation (EGR), Assembly Overview

1 - Potentiometer for EGR -G212

1. Before assembly, check contact surface on intake manifold for contamination and clean, if necessary.
2. After replacing Potentiometer for EGR -G212- ignition must be turned on and then off again. Then, wait one minute for control module after-run (valve is learning, main relay must click during this time)
3. After above replacement procedures, start engine and let run at idle for at least 1 minute.
4. Then, check DTC memory of Engine Control Module (ECM); there must be no DTC stored in memory.

1. If a DTC is stored in memory, erase DTC memory and perform procedure again.

2 - 10 Nm

3 - O-ring

1. Replace

4 - Motor for intake flap -V157

5 - Intake manifold

6 - Seal

1. Replace

7 - Connecting pipe

1. For Exhaust Gas Recirculation (EGR) system

8 - 25 Nm

9 - Radiator

1. For Exhaust Gas Recirculation (EGR) system

10 - 10 Nm

11 - Exhaust manifold

12 - To heat exchanger

13 - From connection fitting

Scheme 39

Exhaust Gas Recirculation (EGR) (Vehicles With Engine Code BKW), Assembly Overview

Note. Exhaust gas recirculation is controlled by Engine Control Module (ECM) J623 and Engine Control Module (ECM) 2 J624 via EGR Vacuum Regulator Solenoid Valve N18 (electro-pneumatic) and EGR Valve 2 N213 (electro-pneumatic) to the mechanical exhaust gas recirculation valves. The mechanical EGR valve with cone-shaped valve plunger makes different opening diameters possible at different valve lift. Components depicted here correspond to cylinder bank 2. They are different only as a mirror image of components for cylinder bank 1.

1 - Intake connection with intake flap motor

Cylinder bank 1

1. Intake Flap Motor V157

Cylinder bank 2

1. Intake Flap Motor 2 V275

2 - 8 Nm

3 - Seal

1. Replace
2. Before installing, check the sealing surfaces for contamination and clean if necessary

4 - EGR Vacuum Regulator Solenoid Valve

1. Checking mechanically --> See «Exhaust Gas Recirculation (EGR) valve (vehicles with engine code BKW), checking»(ref-338222-S08986279272009081800000)

5 - Intake manifold

6 - 20 Nm

7 - Gasket

1. Replace
2. Note installation position

8 - 8 Nm

9 - Exhaust manifold

10 - 8 Nm

11 - 20 Nm

12 - Connecting pipe

Scheme 40

Exhaust Gas Recirculation (EGR) (Vehicles With Engine Code BWF), Assembly Overview

Note. Activation of the Exhaust Gas Recirculation (EGR) system occurs from Engine Control Module (ECM) J623 and Engine Control Module 2 J624 via the EGR Potentiometer G212 and the EGR Position Sensor G466. Components depicted here correspond to cylinder bank 2. They are different only as a mirror image of components for cylinder bank 1. Bypass flap with cooler for Exhaust Gas Recirculation (EGR), assembly overview --> See Bypass flap with cooler for Exhaust Gas Recirculation (EGR) (vehicles with engine code BWF), assembly overview .

1 - Test connection bracket

2 - 8 Nm

3 - Seal

1. Replace
2. Before installing, check the sealing surfaces for contamination and clean if necessary

4 - Gasket

1. Replace
2. Note installation position

5 - To the bypass flap

6 - Connecting pipe

7 - 20 Nm

8 - From the bypass flap

9 - Bracket

For connecting pipe

10 - Connecting pipe

11 - Connecting pipe

12 - 8 Nm

13 - To turbocharger

14 - Exhaust manifold

15 - Intake connection with intake flap motor

Cylinder bank 1

1. Intake Flap Motor V157

Cylinder bank 2

1. Intake Flap Motor 2 V275

16 - EGR Vacuum Regulator Solenoid Valve with EGR Potentiometer

Cylinder bank 1

1. EGR Vacuum Regulator Solenoid Valve N18 (electro-pneumatic) with EGR Potentiometer G212

Cylinder bank 2

1. EGR Valve 2 N213 (electro-pneumatic) with Exhaust Gas Recirculation (EGR) Position Sensor G466

If EGR Vacuum Regulator Solenoid Valve is replaced with EGR Potentiometer , you must then

1. Switch ignition on and off.
2. Then wait for one minute for the control module after-run.
3. Start engine and let run at idle for at least 1 minute.
4. Then, check the DTC memory of the engine control module (ECM).

If a DTC is stored in DTC memory

1. Repeat work procedure.

17 - Intake manifold

Scheme 41

Bypass Flap With Cooler For Exhaust Gas Recirculation (EGR) (Vehicles With Engine Code BWF), Assembly Overview

Note. Hose connections are secured with either spring-type or clamp-type clips. Always replace clamps. The spring-type clip pliers VAS 5024 A are recommended for installing spring-type clips. (Scheme 42)Exhaust Gas Recirculation (EGR), assembly overview --> See Exhaust Gas Recirculation (EGR) (vehicles with engine code BWF), assembly overview.

Scheme 42

Scheme 43

1 - 8 Nm

2 - Vacuum tube

3 - Vacuum line

1. For cylinder bank 2
2. Ensure seated tightly
3. To Exhaust Gas Recirculation (EGR) Cooler Switch-Over Valve 2 N381
4. Connection diagram for vacuum hoses --> See «Vacuum hose connection diagram (vehicles with engine codes BWF)»(ref-338222-S05393684182009081800000)

4 - Vacuum hose

1. For cylinder bank 1
2. Ensure seated tightly
3. To Exhaust Gas Recirculation (EGR) Cooler Switch-Over Valve N345
4. Connection diagram for vacuum hoses --> See «Vacuum hose connection diagram (vehicles with engine codes BWF)»(ref-338222-S05393684182009081800000)

5 - Coolant hose

1. Between cooler for Exhaust Gas Recirculation (EGR) and bypass flap
2. Ensure seated tightly

6 - 40 Nm

7 - Coolant hose

1. Ensure seated tightly
2. Use pliers for spring-type clamps VAS 5024 A to remove and install

8 - 5 Nm

9 - Coolant line

10 - Bracket

11 - 20 Nm

12 - Coolant hose

1. Ensure seated tightly
2. Use pliers for spring-type clamps VAS 5024 A to remove and install
3. To heat exchanger for heater unit

13 - Vacuum actuator

1. For cylinder bank 1
2. Check operation with hand vacuum pump V.A.G 1390 at vacuum connection

14 - Connecting pipe

1. For cylinder bank 1

15 - Connecting pipe

1. For cylinder bank 1

16 - Connecting pipe

1. For cylinder bank 2

17 - Connecting pipe

1. For cylinder bank 2

18 - Gasket

1. Replace
2. Note installation position

19 - Bracket

1. Fastened to cylinder block

20 - Bypass-flap

21 - Vacuum actuator

1. For cylinder bank 2
2. Check operation with hand vacuum pump V.A.G 1390 at vacuum connection

22 - Ball pin, 3 Nm

1. Fastened to flange of generator

23 - Rubber bushing

24 - Bracket

25 - Cooler for Exhaust Gas Recirculation (EGR)

26 - Coolant hose

1. Ensure seated tightly
2. Use pliers for spring-type clamps VAS 5024 A to remove and install
3. From coolant pipe