Checking exhaust gas recirculation valve with temperature sensor — VW

Special tools, testers and auxiliary items

Hand vacuum pump V.A.G 1390
Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
Test box V.A.G 1598/18
Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
Adapter set V.A.G 1594
Current flow diagram

Check conditions

Vacuum pipes and hose connections free of leaks.
Vacuum pipes not blocked/kinked.
Engine oil temperature at least 50 °C

Test sequence

Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit (address word 01); carry out selection at idling:

=> Repair group 01; Self-diagnosis; Connecting fault reader V.A.G 1551 and selecting engine electronics control unit
6-cyl. fuel injection engine, Mechanics
Self-diagnosis
Connecting fault reader V.A.G 1551 and selecting engine electronics control unit

Rapid data transfer
HELP
Select function XX
Indicated on display:

Input 08 for "Read measured value block" function and confirm with Q.

Read measured value block
HELP
Input display group number XX
Indicated on display:

Input 01 for "Display group number" and confirm with Q.

Read measured value block
1
⇒
1
2
3
4
Indicated on display:
(1...4 = Display zones)

Only continue with the test when

The coolant temperature is above 50 °C
-Display zone 2-

Press C key.
Input 02 for "Display group number" and confirm with Q.

Read measuring value block 2
⇒
1
2
3
4
Indicated on display:
(1...4 = Display zones)

Read off figure displayed in display zone 4.
Specification: EGRn. active
(exhaust gas recirculation system not active)
Increase engine speed.
Read off figure displayed in display zone 4.
Specification: EGR active
(exhaust gas recirculation system active)
Pull vacuum hose off (mechanical) exhaust gas recirculation valve.

Connect hand vacuum pump V.A.G 1390 to valve with aux. hose.
Operate pump.
The idling characteristics must noticeably
deteriorate.

If the idling characteristics do not deteriorate:

Press ⇒ button.
Input 06 for "End output" and confirm with Q.
Switch off ignition
Check pipes and connections for blocking, clean, if necessary replace exhaust gas recirculation valve.
Check activation of exhaust gas recirculation valve (N18):

=> Repair group 01; Self-diagnosis; Final control diagnosis
6-cyl. fuel injection engine, Mechanics
Self-diagnosis
Final control diagnosis

Exhaust gas recirculation valve clicks during the final control diagnosis:

Check wiring to exhaust gas recirculation valve temperature sensor (G98):
Remove dash panel insert:

=> Electrical system; Repair group 90
Electrical system

Connect test box V.A.G 1598/18 to control unit wiring loom.

Separate 2 pin connector to exhaust gas recirculation system temperature sensor -arrow-.

Check wiring between test box and 2 pin connector for open circuit according to current flow diagram.
Contact 1+socket 15
Contact 2+socket 33
Wire resistance: Max. 1.5 ω
Check wiring at 2 pin connector for short to one another.
Contact 1+socket 33
Contact 2+socket 15
Specification: ∞ω

If the specifications are attained:

Replace exhaust gas recirculation temperature sensor (G98).
Interrogate fault memory:

=> Repair group 01; Self-diagnosis; Interrogating fault memory
6-cyl. fuel injection engine, Mechanics
Self-diagnosis
Interrogating fault memory