Exhaust Gas Recirculation: Testing and Inspection

EGR VALVE AND EGR TEMPERATURE SENSOR, CHECKING

Special tools, testers and auxiliary items
- VAG 1551 Scan Tool (ST) with VAG 1551/3 adapter cable
- VAG 1390 hand vacuum pump
VAG 1598/18 test box
- VW 1594 connector test kit
- Multimeter (Fluke 83 or equivalent)

Test conditions
- No leaks in vacuum lines and hose connections
- Vacuum lines not blocked or kinked
- Engine oil temperature at least 50 °C (122 °F)
- VAG 1551 scan tool connected; "Engine Electronics" address word 01, "Read Measuring Value Block" function 08; Display Group 002

Test sequence
- VAG 1551 in "Read Measuring Value Block" function 08
- Engine idling

Indicated on display: (1, 2, 3 and 4 = Display fields)

Read measuring value block 2 ->
1 2 3 4





- Disconnect EGR valve vacuum hose from EGR vacuum regulator solenoid valve -1-.
- Connect VAG 1390 vacuum pump to valve.
- Operate vacuum pump to apply vacuum.
- Idle characteristics must get noticeably worse.

If NO:
- Check lines and connections for obstructions, clean if necessary.
- If necessary, replace EGR valve.

If the idle gets worse:
- Read EGR temperature in display field 4.
- Temperature must rise steadily without interruption

The value 127.4 °C will be displayed if there is an interruption, or until this temperature is reached.

- As soon as display reaches 200 °C, disconnect vacuum pump.
- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06.
- Press -Q- button to confirm input.

If the displayed temperature value does not change:
- Switch ignition off.





- Connect VAG 1598/18 test box to ECM wiring harness.
- Disconnect 2-pin harness connector from EGR temperature sensor.
- Check wiring for open circuit between test box and 2-pin connector according to wiring diagram.
- Terminal 1 and test box socket 15
- Terminal 2 and test box socket 33
- Resistance: Max. 1.5 ohm.

- Check wiring between ECM harness connector and 2-pin connector terminal 1 for short circuit to terminal 2 and/or to ground, according to wiring diagram.
- Terminal 1 and test box socket 33
- Specification: infinity ohm (no continuity)
- In addition check wiring for short circuit to battery positive (B+).
Specification: infinity ohm (no continuity)

If no wiring malfunction is found:
- Replace EGR temperature sensor G98.