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 MAF Sensor) in display field 3.
- Connect VAG 1551/1552 Scan Tool and select engine control module, address word 01. Engine must run at idle.
See GENERAL INFORMATION FOR ON BOARD DIAGNOSTIC (OBD) .
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 (MAF) sensor.
See GENERAL INFORMATION FOR ON BOARD DIAGNOSTIC (OBD) .
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 --> button.
- 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, See EXHAUST GAS RECIRCULATION (EGR) VALVE, CHECKING
- Check vacuum hoses, See VACUUM HOSE CONNECTIONS, DIAGRAM