V8 Discovery

Hi all was wondering whether anyone can help me?

I've got a X reg V8 Discovery and when it gets hot and you stop it, then try to start it again it will not start. Leave it for 45 mins and try to start it and will start right up. I've connected a diagnostic machine upto it and all it comes up with is a code in the gearbox which is 023C Can message n_MOT invalid. I've checked the wiring loom that runs up over the gearbox and that is fine. Anybody got any ideas what the code means or the next step to finding the problem?

It seems unlikely that the gbox code is causing your problem.

Does it turn over at normal speed once your try and start it when it's warm or does it turn over slowly?

I'd say it's pointing at an ignition problem - does it run fine the rest of the time?

It does turn over normally just doesn't fire up and runs fine once its started.

There a number of things that have to be right before the ignition relay is energised, amongst these are fuel pressure and a signal from the flywheel sensor.

What happens if any sensor fails, is that the ECU will go into 'get you home' mode, EXCEPT the flywheel sensor. If that dies you're stuck until it is replaced.

In your case I'd start by looking at fuel pump pressure, should be 50psi in old money. Is the fuel pump noisy? can you hear it running?

The ignition relay itself may be faulty also.

The engine ECU also interfaces with other non-engine stuff, like the immobiliser, OBDII socket under the dash and so on.

Peter