How can a ferry cause an EM light ???

[LJ sxi-nav]

Ok, here is the scenario:

120 mile trip to Dover, stopping halfway for 30 minutes. Maintain 6th gear/70mph on cruise for most of the motorway miles. Arrive at Dover and crawl through the ferry port (stop/start 1st gear only) until I drive onto the ferry. takes about 20 minutes from arrival at Dover, crawling in 1st before stopping the car. - NO EM LIGHT seen at all - but I could have missed it, if it only flashed on briefly. (MPG on arrival at Dover 51. By the time I have crawled it is down to 48.5 iirc)

Reasonably calm 90min crossing, bit of choppiness but bothing major.

rejoined car, switched on and EM light is staring at me. Start car to drive off ferry and EM Light goes out.

so a fault has occurred, which as far as I know happened between stopping the car on the ferry, and starting again to drive away. EM light still present, but goes out on engine start - just waiting for the trigger of 25-odd restarts to clear this logged fault.

Is this anything to worry about? Anyone offer any possible reason? Car is normally (day-to-day) driven for 40 miles at a time at 70mph on the work commute. Oh, and the car is going in for a service in 2 weeks to a good independant garage.

[benny]

did you put any french derv in >??

[LJ sxi-nav]

Nope, filled up before I left home.

The EM Light was only seen after switching on the ignition after rejoining the car on the car deck at the end of the crossing to Calais.

very confused! will just put it in for its service next week.

[wardy]

I have heard of florescent lighting in car parks interfering with a car's immobiliser. Can't think of anything else.

[GazVXLINE170]

Sounds daft but I had the EM light on when the car was parked diagonally on a hill. I have seen it where going down a hill in an odd direction does it, may the choppy sea allowed the car to do this for a brief second.

Gazza4

[LJ sxi-nav]

thx for the replies guys, gotta say I think gazza4 is on to something. Maybe as a result of the ferry moving, some sensor picked up an odd reading when i switched on.

i'm just waiting for the light to cure after 25 or so restarts.

[Big Dave]

i'm just waiting for the light to cure after 25 or so restarts.

When I had a logged fault, it took 30 or so days before the light went off without the engine running. I did a lot more than 25 or so starts and I knew the fault was no longer present as it was immobiliser related and the fault only happened the once.

[LJ sxi-nav]

EM light is out! went out on the 16th March, after appearing for the first time on 1st March, so 15 days only, I've worked out it took over 30 restarts, probably closer to 40 tbh.

Anyway, car now serviced, light is out, and all is good! thx to all who replied