Testing exhaust gas recirculation valve -N18: Audi 1.9 TDI (1Z, AHU)

Switch off ignition.
Pull connector off EGR valve -N18
=>Fitting locations overview, Page
23-3
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Testing internal resistance

Set hand-held multimeter V.A.G 1526 to resistance measuring range and connect to valve contacts using test leads from V.A.G 1594 A.
Specification: 4 ... 8ω

If the specification is not attained, renew EGR valve -N18.

Note:

At room temperature the resistance value will be within the lower tolerance range. If the engine is warm, the resistance value will be within the upper tolerance range.

Testing voltage supply

Pull connector off EGR valve -N18
=>Fitting locations overview, Page
23-3
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Set hand-held multimeter V.A.G 1526 to voltage measuring range (20 V direct current) and connect to engine earth and contact 2 of connector using test leads from V.A.G 1594 A.
Switch on ignition.
Specification: approx. battery voltage

If the specification is not attained:

Check fuse 27 in relay panel with fuse holder.
Test for open circuit in wiring between fuse 27 and contact 2 on connector for EGR valve -N18 using current flow diagram.
Test for open circuit in wiring between fuse 27 and excess voltage protection relay -J249 on front auxiliary relay carrier (relay position 14) under dash panel on left-hand side.

Testing activation

Connect voltage tester V.A.G 1527 B to contacts on connector for EGR valve -N18 using test leads from V.A.G 1594 A.
Connect fault reader V.A.G 1551 and select engine electronics control unit=>Page
01-2
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Select the function "Final control diagnosis" and activate EGR valve -N18=>Page
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The LED lamp on the voltage tester should flash.

If the LED lamp does not flash or lights up continuously:

With the ignition switched off, connect test box V.A.G 1598 A to connector for engine control unit but not to the control unit itself (control unit remains disconnected) using adapter V.A.G 1598/5=>Page
23-46
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If the LED lamp does not flash:

Test for open circuit and short to positive in wiring between contact 1 on connector for EGR valve -N18 and socket 6 on test box V.A.G 1598 A.

If the LED lamp lights up continuously:

Test for short to earth in wiring between contact 1 on connector for EGR valve -N18 and socket 6 on test box V.A.G 1598 A.
Rectify any open/short circuit as necessary.