MGF diagnostic tests and procedures

Throttle Position Sensor Re-set

If the throttle body has been recently replaced, or you find that the idle speed is a little on the high side, it may be worth attempting to reset the throttle position sensor (TPS). This is readily achieved by following the following procedure:

1. Start engine and warm engine to its normal operating temperature (essential, as when cold, the engine requires some extra air/fuel - which on the MGF is managed by the idle air control valve: best not confuse the issue!)
2. Now turn off the ignition.
3. Switch on the ignition to position II without starting the engine (all the pre-start warning lights ought to be illuminated)
4. Depress the throttle pedal to the carpet and fully release inside a period of 30 seconds or so.
5. Wait for about 15 seconds...
6. Switch off the ignition

The engine can now be re-started; the TPS has been re-set.

Alarm system test
 

The alarm system can be tested by initiating the alarm system test mode by following the procedure described below:

1. Ensure doors, bonnet and the boot lid are closed.
2. Sit in the driver’s seat and close the door.

NOTE: The next three actions must be carried out within a couple of seconds of one another:

1. Depress the driver’s door lock-pin.
2. Switch the ignition on, off and on again.
3. Raise the driver’s door lock-pin.

If the test mode has been entered correctly, the horns will give a short beep and the engine immobilisation buzzer will sound.

• Opening either door, the bonnet or the boot lid, or operating the driver’s doorsill button, will cause the alarm LED to illuminate for approximately one second. If the LED does not illuminate, there is a system fault.
• The volumetric sensor can also be tested while in test mode. To test the volumetric sensor, press the unlock button on the remote handset several times. The alarm LED will illuminate for approximately 1 second each time movement is detected in the vehicle.

The test mode is cancelled by switching the ignition OFF.
 

Radiator Fan/ MEMS temperature sensor test

If you find your MGF is over heating in slow moving traffic, then a likely cause of this problem is a failure to operate the radiator cooling fan. This is covered in more detail here, but in summary, to test to see whether the problem lies with the sensor or the fan:

1. The radiator is typically inaudible from the driver's seat, so a simple test to see whether it is working correctly, is to switch on the engine and allow it to idle for 45 minutes. Normal engine temperature is achieved within 30 minutes of idling, and within 45 minutes, sufficient heat should build within the cooling system to require additional cooling via the radiator. The cooling fan will either come on (audible from in front of the car), OR the engine will start to over heat.
2. Having established that the radiator is failing to come on, remove the engine cover and disconnect the brown coloured water temperature sensor that is located on the water outlet on the front left hand corner of the engine. Whether hot or cold, doing this will immediately start the fan. If not, either there is a problem with the fuses or the fan circuit itself.