Auxiliary Cabin Heater Overheat Sensor / Switch: Service and Repair

Overheat protection thermostat/flame sensor/engine coolant temperature sensor, replacing

As the illustrations in this service information are used for different model years and/or models, some variation may occur. However, the essential information in the illustrations is always correct.

Removing the overheat protection, thermostat flame sensor and coolant temperature sensor





Remove:
- the bumper cover. See Casing bumper front, replacing Service and Repair
- the heater. See Engine coolant heater, replacing Engine Coolant Heater, Replacing
- the nut and the cover.

Remove:
- the engine coolant temperature sensor (1) by working it loose
- the overheat protection thermostat (2) by slackening off a nut.




- the control module. See Control module engine coolant heater, replacing Service and Repair.

Remove:
- the hose clamp from the intake hose
- the three screws from the fan shroud. Lift the fan shroud out.




Disconnect the fan motor connector.
Disconnect the flame sensor from the mounting.





Replacing the entire cable harness:
Remove the entire cable harness forallsensors.

Hint: Replace the cable harness by removing it piece by piece. Replace in the same order with a new cable harness so that it is correctly positioned.

Cutting and splicing the cable harness:
To replace individual sensors, cut and splice the cable harness. See Splicing the cables Splicing the Cables.

Installing the overheat protection, thermostat flame sensor and coolant temperature sensor

Install:
- the new cable harness
- all the sensors and connectors
- the fan shroud
- the intake hose
- the control module. See Control module engine coolant heater, replacing Service and Repair
- the overheat protection thermostat using a nut (1xM5). Tighten. See Tightening torque [1][2]Body and Frame
- the engine coolant temperature sensor
- the cover with a nut. Tighten. See Tightening torque [1][2]Body and Frame
- the heater. See Engine coolant heater, replacing Engine Coolant Heater, Replacing.

Final check
Test run the heater. Check the function of the heater. See Engine coolant heater, test running Component Tests and General Diagnostics.
Check that no diagnostic trouble codes (DTC) have been stored during the repair work.
Install the bumper cover. See Casing bumper front, replacing Service and Repair.