Checking potentiometer for exhaust gas recirculation — VW

Special tools, workshop equipment, test and measuring appliances and auxiliary items required

V.A.G 1526 Hand multimeter
V.A.G 1527 B Diode test lamp
V.A.G 1594 A Adapter set
V.A.G 1598/31 Test box
Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
Current flow diagram

Test conditions

The fuses must be OK.

The battery voltage must be at least 11.5 V.

Test sequence

Pull off 6-pin connector -arrow- (grey) from EGR valve.

Connect multimeter to measure voltage between contacts 2 (positive) and 4 (earth) of connector using adapter cables from V.A.G 1594 A.
Switch on ignition.
Specification: min. 4.5 V

If the specification is not attained:

Switch off ignition.

First check whether a coded radio is fitted. If this is the case obtain the anti-theft coding.
Remove battery.
Connect test box V.A.G 1598/31 to control unit wiring harness. The engine control unit remains disconnected.

Check wiring for open circuit between test box and 6-pin connector using current flow diagram.
Contact 2 and test box socket 98
Contact 4 and test box socket 108
Contact 6 and test box socket 100
Wire resistance: max. 1.5 ω
Additionally check wiring for short to one another, and for short to positive or earth.

If the specification is obtained:

Connect test box V.A.G 1598/31 to engine control unit as well and reconnect 6-pin connector to EGR valve.
Install battery.
Connect the fault reader V.A.G 1551 (V.A.G 1552). Then switch ignition on and select engine control unit with the "Address word" 01.

=> Repair group 01; General to self-diagnosis: Connecting fault reader
4-cyl. injection engine (2 valve without intermediate shaft), Mechanics
General to self-diagnosis: Connecting fault reader

Initiate final control diagnosis and select EGR valve (N18):

=> Repair group 01; Final control diagnosis; Performing final control diagnosis
4-cyl. injection engine (2 valve without intermediate shaft), Mechanics
Final control diagnosis
Performing final control diagnosis

Connect diode test lamp V.A.G 1527 B to socket 100 of test box and earth using adapters from V.A.G 1594.
The LED must flash.
Proceed with final control diagnosis until completed.
Press keys 0 and 6 for the function "End output" and confirm entry with the Q key.
Switch off ignition.

Depending on conditions, renew following components:

LED flashes:

Renew EGR valve (N18) with potentiometer (G212).
Re-adapt engine control unit:

=> Repair group 24; Engine control unit; Adapting engine control unit to throttle valve control part and EGR valve
4-cyl. injection engine (2 valve without intermediate shaft), Mechanics
Engine control unit
Adapting engine control unit to throttle valve control part and EGR valve

If no wiring fault is detected and the LED does not flash:

Renew engine control unit:

=> Repair group 24; Engine control unit; Renewing engine control unit
4-cyl. injection engine (2 valve without intermediate shaft), Mechanics
Engine control unit
Renewing engine control unit