Code 78 (Coolant Temperature Sensor)

ENGINE TEMPERATURE SENSOR (COOLANT)
Explanation
This trouble code is stored in the case of a short or break occurring at the temperature sensor or on its supply wires. A prerequisite for detecting a short to positive or a break, the plausibility of the coolant and the intake air temperature is checked.

NOTE: After defect detection, a substitute value of 122°F (50°C) is used.

Troubleshooting
- Check temperature values by means of status monitoring. If not plausible: Check wire to Digital Motor Electronic (DME) Pin 78 and temperature sensor.
- Proceed with displayed scan tool diagnostic instructions where applicable.