Audi Workshop Service and Repair Manuals

Electrical test of exhaust gas recirculation valve -N18- and exhaust gas recirculation potentiometer -G212-

Special tools and workshop equipment required

t	Hand-held multimeter -V.A.G 1526 B- or -V.A.G 1526 A-

t	Voltage tester -V.A.G 1527 B-

t	Auxiliary measuring set -V.A.G 1594 C- or -V.A.G 1594 B-

t	Adapter cable, 121-pin -V.A.G 1598/31- (test box)

t	Vehicle diagnosis, testing and information system -VAS 5051 A- with diagnosis lead -VAS 5051/1-

Checking internal resistance –  Take off engine cover panel -arrows-.

–  Unplug electrical connector -arrow-.

–  Connect up multimeter for resistance measurement as follows.

Component	Connector Contact	Specification at room temperature
Exhaust gas recirculation valve -N18-	-1- + -5-	7.5 … 8.5 Ω
Potentiometer for exhaust gas recirculation -G212-	-2- + -4-	2.6 … 4.8 Ω
	-2- + -6-	0.5 … 6.3 Ω

If the specifications are not obtained: –  Renew the exhaust gas recirculation valve -N18- with exhaust gas recirculation potentiometer -G212- → Chapter. If the specifications are obtained: –  Check voltage supply of exhaust gas recirculation valve -N18-. Checking voltage supply for exhaust gas recirculation valve -N18- l  Check that power supply relay for Simos control unit -J363- is OK.

l  Fuse in fuse holder -S237- (position 37) OK.   Note The power supply to the exhaust gas recirculation valve is provided by the current supply relay for Simos control unit -J363- via fuse in fuse holder -S237-.

–  Connect voltage tester -V.A.G 1527 B- between contact -1- and earth. –  Switch on ignition. l  The LED should light up. –  Switch off ignition.

If the LED does not light up: –  Check the wiring from contact “1” of the connector to the power supply relay for Simos control unit -J363--item 2- (below cover on left side of bulkhead) for open circuit using the current flow diagram. –  Repair wiring connection if necessary. If the LED lights up: –  Check voltage supply of exhaust gas recirculation potentiometer -G212-.

Checking voltage supply for exhaust gas recirculation potentiometer -G212- –  Connect multimeter between contacts -2- and -4- of connector to measure voltage. –  Switch on ignition. l  Specification: 4.5 ... 5.5 V –  Switch off ignition. If specification is not obtained: –  Connect adapter cable, 121-pin -V.A.G 1598/31- (test box) to connectors of wiring harness; do not connect engine control unit. Connect earth clip of test box to earth → Rep. Gr.24.   Caution To avoid damage to the electronic components, select the required measuring range and observe test conditions before connecting the test leads.

–  Check for open circuit and short to positive or earth in the following wiring:

Connector Contact	Adapter cable, 121-pin -V.A.G 1598/31- (test box) Socket
-2-	96
-4-	84

–  Repair wiring connection if necessary. If wiring is OK: –  Renew engine control unit. Checking signal wire between exhaust gas recirculation potentiometer -G212- and engine control unit –  Connect adapter cable, 121-pin -V.A.G 1598/31- (test box) to connectors of wiring harness; do not connect engine control unit. Connect earth clip of test box to earth → Rep. Gr.24..   Caution To avoid damage to the electronic components, select the required measuring range and observe test conditions before connecting the test leads.

–  Check for open circuit and short to positive or earth in the following wiring:

Connector Contact	Adapter cable, 121-pin -V.A.G 1598/31- (test box) Socket
6	108

–  Repair wiring connection if necessary.

Checking activation of exhaust gas recirculation valve -N18- l  Voltage supply OK. –  Connect voltage tester -V.A.G 1527 B- to contacts -1- and -5- of the connector. –  Connect up vehicle diagnostic, testing and information system -VAS 5051 A- with diagnosis lead -VAS 5051/1- and select vehicle system “01 - Engine electronics” from list. When doing this, the ignition must be switched on.

Display on -VAS 5051 A- –  From the menu -1- select the diagnostic function “03 - Final control diagnosis”.

Display on -VAS 5051 A- –  Keep touching the → key until the following display appears: A -  3rd control element in test 3 -  Exhaust gas recirculation valve -N18- –  Press the → key again. A -  Actuator is running; continued switching is allowed l  LED should flash slowly.   Note Voltage testers with a low current draw do not go out completely between activation signals from engine control unit, but continue to glow slightly and become distinctly brighter on activation. –  Exit function “03 - Final control diagnosis” by pressing the ← key. –  Press “06 - End output”. –  Switch off ignition. If the LED does not flash: –  Connect adapter cable, 121-pin -V.A.G 1598/31- (test box) to connectors of wiring harness; do not connect engine control unit. Connect earth clip of test box to earth → Rep. Gr.24.   Caution To avoid damage to the electronic components, select the required measuring range and observe test conditions before connecting the test leads.

–  Check for open circuit and short to positive or earth in the following wiring:

Connector Contact	Adapter cable, 121-pin -V.A.G 1598/31- (test box) Socket
5	115

–  Repair wiring connection if necessary. If wiring is OK: –  Renew engine control unit.