Checking exhaust gas recirculation valve and temperature sensor — VW

Checking activation of two-way valve (N18):

=> Repair group 01; Self-diagnosis; Final control diagnosis
4-Cyl. Injection Engine, Mechanic
Self-diagnosis
Final control diagnosis

Special tools, testers and auxiliary items

Fault reader V.A.G 1551 with cable V.A.G 1551/3
Hand vacuum pump V.A.G 1390
Test box V.A.G 1598/18
Adapter set V.A.G 1594
Hand multimeter V.A.G 1526 or multimeter V.A.G 1715

Test conditions

Vacuum pipes and hose connections not leaking.
Vacuum pipes not blocked or kinked.
Engine oil temperature at least 50 °C.
Fault reader V.A.G 1551 connected and brought into "Read measuring value block" function (display group number 02)

=> Repair group 01; Injection and ignition system; self-diagnosis
4-Cyl. Injection Engine, Mechanic
Injection and ignition system
self-diagnosis

Test sequence

Carry out check with fault reader V.A.G 1551 in function 08, "Read measuring value block", with engine idling.

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

Pull exhaust gas recirculation valve vacuum hose off two-way valve -1-.
Connect vacuum pump V.A.G 1390 to valve.
Operate vacuum pump. The idling speed behaviour must deteriorate noticeably.

If no change is detected:

Check pipes and connections for blockage, clean, if necessary replace exhaust gas recirculation valve.

If the idling behaviour does deteriorate:

Read-off temperature value for exhaust gas recirculation valve in display zone 4. The temperature value must increase uniformly without interruption.
127.4 °C will be displayed if interrupted and when this temperature has not been reached.
As soon as 200 °C has been attained, remove vacuum pump.
Press ⇒ button.
Input 06 for "End output" function and confirm with Q.

If the temperature value does not change:

Switch off ignition

Connect test box V.A.G 1598/18 to control unit wiring loom.
Pull 2 pin connector off temperature sensor.
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 wire between control unit connector and 2 pin connector contact 1 for short to wire contact 2 and to vehicle earth, according to current flow diagram.
Contact 1+socket 33
Specification: ∞ω
Additionally check wiring for short to battery positive.
Specification: ∞ω

If no fault in wire is detected:

Replace temperature sensor (G98) => Page
26-13
Item
1