30 Engine Compartment Temperature - Below Limit

P1157

30 Engine Compartment Temperature - Below Limit

Function
A temperature sensor is installed to measure the engine compartment temperature. With these DTC's, the wiring from the DME control module, pin II/21, to the ECT sensor, pin 1, is monitored.

Diagnosis conditions

P1157
After a debounce time of 2 seconds, a fault is stored if an engine compartment temperature < of 42 °C is measured.

P1158
After a debounce time of 2 seconds, a fault is stored if an engine compartment temperature of > 135 °C is measured.

P1157 - P1158:

Wiring Diagram







Diagnosis Procedure







1 Check ECT sensor.
1. Remove connector of ECT sensor.
2. Connect ohmmeter to ECT sensor, pins 1 and 2.

Display: approx. 2.2 - 2.6 k ohms at 20 °C

2 Check wiring from DME control module, pin II/21, to ECT sensor for short circuit to ground.
1. Connect special tool 9637 to wiring harness (DME control module connector).
2. Remove connector of ECT sensor.
3. Connect ohmmeter to special tool 9637, pin II/21, and ground.

Display: infinity ohms

If 0 - 5 ohms is displayed, check wiring harness for chafing and pinching damage.

2 Check wiring from DME control module, pin II/21, to ECT sensor for short circuit to B+.
1. Connect special tool 9637 to wiring harness (DME control module connector).
2. Remove connector of ECT sensor.
3. Connect voltmeter to special tool 9637, pin II/21, and ground.

Switch on the ignition.
Display: 0 V

If battery voltage is displayed, check wiring harness for chafing and pinching damage.

4 Check output voltage from DME control module.
1. Connect special tool 9637.
2. Remove connector of ECT sensor.
3. Connect voltmeter to pin II/21 (B+) and III/17 (ground).

Switch on the ignition.
Display: approx. 5 V

5 Perform adaptation.
1. Switch on the ignition.
2. Wait one minute. Do not press the accelerator.
3. Switch off the ignition for at least 10 seconds.
4. Read out the fault memory.