Exhaust Gas Recirculation: Testing and Inspection

Exhaust Gas Recirculation (EGR) valve, checking

Special tools and equipment



^ VAG 1390 Hand vacuum pump




^ VAG 1921 Spring clamp pliers

Test sequence



- Remove clamp -1- at intake manifold -2-.
- Remove vacuum hose from EGR valve.
- Connect hand vacuum pump V.A.G 1390 to EGR valve.




- Operate hand pump and observe membrane rod.
^ Membrane rod must move in direction of arrow.
- Disconnect vacuum pump hose from EGR valve.
^ Membrane rod must move back against direction of arrow to its original position.
If the membrane rod does not move:
- Replace EGR valve and control flap

Exhaust Gas Recirculation System, checking





Special tools and equipment
^ Fluke 83 multimeter
^ VW 1594 Adaptor kit
^ VAG 1598/22 Test Box
^ VAG 1551/1552 Scan Tool with VAG 1551/3 adaptor cable
^ Wiring diagram

Requirements





- Fuse No. 34 OK.
^ Battery voltage must be at least 11.5 V
^ No leaks in intake and exhaust system.
^ No malfunctions in the engine or fuel injection system such as start of injection, injectors, compression pressures.
^ The engine coolant temperature must be at least 85°C (185°F).

Test sequence
Testing the EGR system is done in function 04 (Basic setting). This procedure activates the EGR valve every 10 seconds to make it possible to read the extreme values for EGR (Mass Air Flow MAP Sensor) in display field 3.
- Connect VAG 1551/1552 Scan Tool and select engine control module, address word 01. Engine must run at idle.





Indicated on display
- Press buttons -0- and -4- to select "Basic setting" function 04.
- Press -Q- button to confirm input





Indicated on display
- Press buttons -0-, -0- and -3- to select "Display group 3".
- Press -Q- button to confirm input





Indicated on display: (1 to 4 = Display fields)
^ Display in field 2 must fluctuate every 10 seconds between EGR active or EGR inactive (n.aktiv).
The displays in display fields 3 and 4 must fluctuate within the following control range:

Note: If a constant value of 550 mg/H is indicated in display field 3, check Mass Air Flow (MAP) sensor.

If EGR NOT active:





Specified value in display field 3:420 to 560 mg/stroke
^ Specification in display zone 4:0 to 5%
If EGR active





Specified value in display field 3:170 to 340 mg/stroke
Specification display zone 4:95 to 100%
- Press Rebutton.
- Press buttons -0- and -6- for to select "End output" function 06.
- Press -Q- button to confirm input.
- Switch ignition off.
If specifications are not obtained:
- Check mechanical EGR valve
- Check vacuum hoses

EGR Vacuum Regulator solenoid valve, checking





- Disconnect 2-pin electrical connector from EGR valve (arrow).

Resistance, measuring





- Measure resistance between contact terminals of -N18- EGR Vacuum Regulator Solenoid Valve.
^ Specification: 14.0 to 20.0

Note: At room temperature resistance is in the lower tolerance range. At operating temperature resistance is in the upper tolerance range.

If specification not obtained:
- Replace EGR Vacuum Regulator solenoid valve -N18-.
- Check DTC memory.
- Read readiness code.
If the DTC memory was erased or the engine control module is subject to low voltage with the ignition ON, reset the readiness code again.
If the specification was obtained:
- Check voltage supply of EGR valve

Voltage supply, checking





- Connect multimeter using jumper wire from VAG test kit between terminal 1 and engine Ground (GND).
- Switch ignition ON.
^ Specification: at least 11.5 V
If the specification was not obtained:
- Switch ignition off.
- Remove windshield wiper arms and plenum cover.





- Connect VAG 1598/22 Test Box to harness connector of control module.





- Check wiring for short circuit between Test Box sockets.
^ Resistance: 1.5 Ohm maximum
- Check wires for short circuit one against another, to vehicle ground and to battery B+.
^ Wiring resistance: x
If no malfunction and if voltage between terminal 1 and ground:
- Replace Diesel Direct Fuel Injection (DFI) Engine Control Module -J248-.
- Check DTC memory.
- Read readiness code.
If the DTC memory was erased or the constant voltage supply to the engine control module was interrupted, the readiness code must be initiated again.