Over the last few months, this problem has become more regular. When I turn the key, the coil light comes on. It normally turns off almost immediately. However, more recently, it's been on for about 20 seconds before going off. Then, when I turn on the ignition, the car revs much higher than normal, before quickly settling back to normal tickover revs.

Given the coil light staying on, and the behaviour of the engine revving up, I guess it's not a timing issue or a glow plug issue. Does anyone know what else it could be please? Maybe a sensor of some sort?

Mine always takes longer the colder the outside temp. In the summer, it merely flashes on before it goes again.

Could that be it......tech's, someone, anyone...

Sounds like its on cold running, could be a faulty temp sensor or just the fact that its got colder. 20 seconds is the heating period for cold weather, its also the default time if you disconnect the coolant temp sensor to test the glow pugs.

The glow plugs will only come on fully if they are required. They then come back on when the engine is warming up, this prevents diesel knock and helps the car get up to temp. The light however doesnt display this operation.

cool, thanks. I suspect it may be temp related, although the fact it also revs up to maybe 1500 revs or so on ingition seems a bit strange. Will leave it for now and see how it acts in the spring/summer time (due a service in may so maybe good timing)