| No. | TECH 1 | Checking Conditions | Nominal Values | Trouble | Terminal |
|---|---|---|---|---|---|
| Display | Codes | ||||
| 08 | 02 SENSOR* | Ignition ON, oxygen sensor cold | 350 to 550 mV | 13, 44,45 | D 7/D 6 |
| Engine at idle speed, | 50 to 950 mV | ||||
| operating temperature | (alternating) | ||||
| During test drive only: | 500 to 1000 mV | ||||
| At full load under 4000 rpm | 50 to 950 mV | ||||
| At full load above 4800 rpm | (alternating) |
Trouble-shooting: Nominal Value: Cause of Fault:
(If nominal value is not attained)
· Separate wiring harness 300 to 550 mV · Lead interruption from control unit K 100 Ter. D 7
plug from oxygen sensor. to wiring harness plug at oxygen sensor.
Measure voltage (20V/DC) - Lead interruption from control unit K 100 Ter. D 6
at wiring harness plug to ground (with display 800 to 1000 mV)
with multimeter - Short circuit between K 100 Ter. D 7 and ground.
Ignition ON. - Control unit defective.
· Engine in TECH 1 mode "F7", 50 to 950 mV · Oxygen sensor defective.
submode "F0". Adjust to 1300 rpm
using arrow keys. - Mixture constantly too lean/rich
Measure voltage (20V/DC) at
oxygen sensor plug
with multimeter (oxygen sensor plug
separated). Accelerate briefly. When accelerating
briefly > 700 mV
* If the oxygen sensor is wrapped in aluminium foil, remove the foil.
Trouble-shooting: Nominal Value: Cause of Fault:
(If nominal value is not attained)
Mixture constantly too rich
(oxygen sensor voltage > 600 mV)
· Check fuel pump pressure Feed pressure: 0.7 to 0.8 bar · Return line blocked/kinked
Return pressure: < 0.3 bar - Leaky injection valve
(injection valve continues dripping)
- Insulation on cable guide to injection
valve chafes on injection housing
(loose contact to ground)
- Active carbon canister or line to injection
housing leaky.
- Active carbon canister valve defective
- Temperature sensor P 30 defective
(see test step 02)
- Intake manifold pressure sensor defective
(see test step 03)
- Intake manifold pressure sensor hose leaky,
blocked, sealed off.
- Throttle valve potentiometer defective
(see test step 04)
- Fuel pressure regulator defective.
If everything up to here OK then:
· Internal exhaust gas · Check timing of valves and examine for leaks.
recirculation rate too large
- Control unit defective
Trouble-shooting: Nominal Value: Cause of Fault:
(If nominal value is not attained)
Mixture constantly too lean
(oxygen sensor voltage < 300 mV)
· Check fuel pump pressure Feed pressure: 0.7 to 0.8 bar · Supply line blocked/kinked
Return pressure: < 0.3 bar - Injection valve blocked or defective
- Connecting line from air cleaner
to throttle valve housing leaky.
- Active carbon canister or line to
injection housing leaky.
- Intake manifold pressure sensor defective
(see test step 03)
- Intake manifold pressure sensor hose defective.
- Temperature sensor P 30 defective
(see test step 02)
- Throttle valve potentiometer defective
(see test step 04)
- Fuel pressure regulator defective.
- Intake system leaky
- Exhaust system leaky
- Poor fuel quality
- Control unit defective