Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Control Module
The key role of the additional and parking heater (combustion preheater module) is to manage the function for:
- Additional heater
- Parking heater
- Electrical heater
- Residual heater
- Remote start.
The same control module is used for both the additional heater and the parking heater. Depending on the vehicle configuration, the heater can function as an additional heater or as a parking heater. The additional heater is standard in some markets (cold climates). The heater which uses radiant heat from the engine is not capable of maintaining a comfortable passenger compartment temperature.
The control module is positioned in the front left corner of the car in front of the wheel. A large number of the heater functions are controlled by the central electronic module.
The combustion preheater module communicates partly with components which are directly connected and partly with other control modules and components via serial communication.
The combustion preheater module is not a CAN node. It is a slave node of the central electronic module which uses serial communication.
The control module checks activations and input and output signals through an integrated diagnostic system Diagnostic trouble codes (DTCs) are validated in the combustion preheater module if the control module detects an error. In certain cases the control module replaces the faulty signal with a substitute value.
Any diagnostic trouble codes (DTCs) are then sent to the central electronic module where they are stored. The data can be read off using the diagnostic tool.
A simple way to check that the combustion preheater module is supplied with power is to activate the heater. On cars with a parking heater the heater can be activated using the control stalk on the steering wheel. For cars with an additional heater, use the diagnostic tool to activate the heater. The diagnostic tool can be used to start the heater even if diagnostic trouble codes (DTCs) which would prevent the heater from starting are stored.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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