Engine Temperature Sensor - Signal Implausible

P0115

Engine Temperature Sensor - Signal Implausible

Function
The temperature sensor measures the coolant temperature by means of a variable resistor.
The engine coolant temperature is required for regulating the warm-up phase, for mixture enrichment on start-up, for calculating the ignition angle in the warm-up phase and for controlling the fans. In the event of a fault, a calculated substitute characteristic is used.

Diagnosis conditions

P0115
60 seconds after start-up, inertia fuel shutoff. A fault is recorded after a debounce time of 0.4 seconds if the measured engine temperature is lower than the calculated engine temperature minus approx. 10 °C.

P0117
A fault is recorded after a debounce time of 0.4 seconds if an engine temperature of less than -42 °C is measured.

P0118
A fault is recorded after a debounce time of 0.4 seconds if an engine temperature of more than 140 °C is measured.

P0115-P0118:

Wiring Diagram







Resistance values
0 °C = 5.0 - 7.0 kohms
20 °C = 2.0 - 3.0 kohms
60 °C = 0.4 - 0.8 kohms

Diagnosis Procedure

DTC P0115







DTC P0117







DTC P0118







1 Check temperature sensor.

1. Remove connector in engine compartment.
2. Connect ohmmeter to temperature sensor at pins 1 and 4.
Display: 2 - 3 kohms at 20 °C.

2 Check output voltage of DME control module.

1. Connect special tool 9616.
2. Connect voltmeter to pin 74 (positive) and 34 (negative).
3. Ignition on.
Display: approx. 5 V

3 Check wiring from DME control module to temperature sensor for continuity.

1. Connect special tool 9616 to wiring harness (DME control module connector).
2. Remove connector of temperature sensor.
3. Connect ohmmeter to special tool 9616, pin 34, and temperature sensor connector, pin 4.
Display: 0 - 5 ohms

4. Connect ohmmeter to special tool 9616, pin 74, and temperature sensor connector, pin 1.
Display: 0 - 5 ohms

4 Check wiring from DME control module to temperature sensor for short to ground.

1. Connect special tool 9616 to wiring harness (DME control module connector).
2. Remove connector of temperature sensor.
3. Connect ohmmeter to special tool 9616, pin 74, and to ground, pin 6.
Display: Infinity ohm

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

5 Check wiring from DME control module to temperature sensor for short to B+.

1. Connect special tool 9616.
2. Remove connector of temperature sensor.
3. Connect voltmeter to pin 74 (B+) and to ground, pin 6.
4. Switch on the ignition.
Display: approx. 5 V

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