Intermittent loss of engine power

[Paul Coleman]

My Dad's 2013 petrol Fiesta has a strange problem where it will sometimes lose engine power whilst driving if you switch the lights on (either side or headlights). I have tried switching the heated windows on whilst driving but that doesn't case the problem. It's almost as though it goes into limp home mode but after 5 to 10 seconds it will pick up again on its own. I have checked the ecu codes and there aren't any. I've searched the internet but haven't been able to find a common fault and if he puts it into a garage it will probably cost more than the car's worth!!

If anybody has had a similar problem and been able to fix it I'd be interested to hear from you.

Thanks in advance, Paul.

[Paul Coleman]

For reference - it turned out to be a bad earth on the rear lights.