Engine Compartment Temperature Sensor - Short Circuit to B+

P1158

Engine Compartment Temperature Sensor - Short Circuit to B+

Function
The ECT sensor measures the engine compartment temperature. With these DTC's, the wiring from the DME control module, pin 16, to the ECT sensor, pin 1, is monitored.

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 [>] 143 °C is measured.

P1157-P1158:

Wiring Diagram







Resistance value
2.2 - 2.6 kohms at 20 °C

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 kohms at 20 °C

2 Check wiring from DME control module to ECT sensor for short to ground.

1. Connect special tool 9616 to wiring harness (DME control module connector).
2. Remove connector of ECT sensor.
3. Connect ohmmeter to special tool 9616, pin 16, and ground.
Display: Infinity ohm

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

3 Check wiring from DME control module to ECT sensor for short circuit to B+.

1. Connect special tool 9616 to wiring harness (DME control module connector).
2. Remove connector of ECT sensor.
3. Connect voltmeter to special tool 9616, pin 16, 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 9616.
2. Remove connector of ECT sensor.
3. Connect voltmeter to pins 16 (positive) and 34 (negative).
Switch on the ignition.
Display: approx. 5 V