After putting up with the dreaded 'check engine' light (MIL) for a while, I paid £24 to have the code read by a local garage. They found the code P0480, which is apparently due to a Low Speed Cooling Fan Relay Circuit Fault.

Having checked that the high-speed fan circuit works by switching on the air conditioning, the garage cleared the fault code and advised me to keep an eye on the temperature gauge (which always looks fine at just below half way once the engine has warmed up).

However, the MIL lit up again as I was driving home from the garage. I decided to invest in a gadget from Amazon called ODBMATE OM123, which cost about £26. It plugs into the diagnostic socket under the glove compartment, and allows you to read and erase the check engine codes, and see data about your engine in real time (e.g. rpm, temperature, etc.).

But my MIL kept coming back with the P0480 code every time I erased it, and I naturally fretted about the engine possibly overheating due to this fault.

Then I cleared the check engine light an sat on the drive with the engine running while listening carefully, and watched the live data feed telling me the temperature of the engine. I could hear the low-speed fan switching on and off periodically. It comes on at about 93 degrees C and switches off again at about 88 degrees C. So clearly works and is operated by some sort of thermostat. And the check engine light stayed off. I was relieved and thought my problems were over.

But the check engine light came on again as soon as I set off and got 100 yards down the road, and the same error code P0480 showed up on the scanner again.

Mysterious points:

1) The service manual says that this DTC should not illiminate the MIL, but it does for me.

2) The fan seems to work be working perfectly well, yet the DTC reappears every time I clear it.

3) The DTC/MIL does not come on if I just sit on the drive with the car running. It only occurs after a minute or two driving.

Well if anyone out there has any ideas, I would be really grateful to hear them.