Description of function of the operating status of the heater
The heater can have a number of different statuses. Each status and what should occur in it is described below.
| Operating status: | Description: |
| 0: The heater has not started | Initialization of the combustion preheater module (CPM). |
| 1: The heater starts | Heater self test. The glow plug and the water pump are activated. The combustion fan then starts at low speed to ventilate the heater. This is to cool the glow plug so that the flame sensor does not detect light from the glow plug as a flame. The control module pulses the supply to the glow plug (pulse width modulation (PWM) signal). The glow plug is sufficiently warm to ignite the fuel after approximately 45 seconds. This whole process takes approximately 1 minute. |
| 2: The heater starts and the fuel pump is active | The fuel pump starts and the speed of the combustion fan increases. The control module waits for a flame. The blower fan will now be running. Maximum time 1 minute. |
| 3: The heater runs | A flame has been detected by the flame sensor and heats the heater. When the car is being driven the heater is stopped if the engine coolant temperature (ECT) exceeds a certain level. The heater is stopped by cutting the fuel supply. The combustion fan ventilates the heater when the flame has gone out. When the temperature falls below a certain level, the heater starts again. This means that the heater cycles between 2 temperature ranges. |
| 4: The heater stops | The fuel pump stops, the flame is extinguished and the heater is ventilated. |
| 5: The heater waits | Waiting for the engine coolant temperature (ECT) to fall low enough for the heater to start again. |
| 6: The heater has stopped | The heater only has this status if a fault has occurred. |
| 7: The flame is extinguished | The flame has gone out while the car is being driven. |
| 8: Residual heat | If, when the outside temperature is low, the driver is in the car and turns on the heater, the water pump starts in order to heat the passenger compartment. |
| 9: Fuel pump activated | Used in production. |
| 10: Activating the fuel pump | Single pulses to the fuel pump are used to prevent the fuel pump sticking. |
The vehicle configuration can be read off to check what functions the car is equipped with. The following affect the function of the heater:
- Parking and additional heater function or additional heater function only (diesel engines)
- Parking heater or not (gasoline engines)
- Residual heater or not
- Electrical engine block heater (time controlled via the driver information module (DIM)) or not.