Re: car people only please...

It can be a nuisance if the ECU switches to 'get you home' mode and the car then does not run properly. Used to happen to my wife's Golf. By the time you got to a VW garage the fault had cleared.

Our diesel Fiesta is not that clever. However, engine torque is much reduced while the filter is being cleaned. On long trips it would remain in this mode unless the engine is switched off and back on!

With careful use of the clutch, this can be done on the move:-)

Common one on my last car was the crank position sensor - a hall effect type - having an intermittent fault. Likely something akin to a dry joint. When that happened, the ECU got its tach signal from the cam sensor only and went to limp home mode. Fixed timing for ignition and injection. But would often clear itself after the engine cooled down. Luckily, the fault code was stored. That car had 3 CPS in the 15 or so years I owned it.

I've had a warning about my AdBlue heater for two years now. I believe the heater is broken, but since the freezing temp of AdBlue is -11C, I can live with that. My garage reset the code every time when they do an MoT.

When I had a coil pack fail on a car I had fault codes completely unrelated to my car (diesel related faults on a petrol car).