7G-DCT throws a wobbly

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HumberMart

Active Member
Joined
Jan 1, 2010
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447
Location
North Lincolnshire
Car
CL500 4.7 twin turbo
Of course we picked a great moment to try and drive to the S of France what with all the snow, but worse than that car trouble as well.

Not expecting snow, using the B and its 50+ mpg seemed the best option for a 2,000 mile round trip to Banyuls Sur Mer rather than the ML. The B did well through the snow and seeing 54 mpg on the computer was enough to overcome the fear of not having all the metal around of the 4x4.

Finally stopped for fuel in Millau, before crossing the bridge and had to crawl up the hill back to the bridge at 20 mph. Thought we must have got duff gas oil. No engine lights but couldn't get it to rev above 3K.

Was very tired by then and looking to bed down for the night but the car was full of stuff and the thought of calling the recovery service not very appealing so decided to drive on and use some fuel in the hope we could dilute it with better, assuming that was the problem.

During the next 100 miles I began to doubt the fuel being the cause. It was almost too coincidental not to be but the car ran well if you kept the revs below 2,500 and the fact that there were no lights on the dash warning me of any problems was baffling.

After stopping at a toll booth I put my foot down a bit too quickly and the car just stuck in one gear at 3,000 rpm and wouldn't stop!

Even with no pressure on the accelerator it just kept going on its own and I only managed to stop it by using the paddles to force it into a higher gear and lower revs!

I was then convinced it must be the DCT or at least a sensor fault.

So we battled on and got to Banyuls. Then as strangely as the problem had started in Millau it cleared itself this morning after a nights rest.

Not sure if it was selecting reverse or something that had caused it to correct itself or a few hours of sleep. I'd tried turning it off and on again and all different settings on the gearbox whilst it was playing up, but no joy.

Of course we'll take it for a full check up when we get back, assuming no more issues, and hopefully get a star diagnosis.

Mind you, we were discussing swapping it for a CLS just before Millau so maybe it overheard!
 
Of course we'll take it for a full check up when we get back, assuming no more issues, and hopefully get a star diagnosis.
Hope you make it back without further issues. Question for those who know these things: are fault conditions stored indefinitely on MB ECU's until cleared with STAR, or do they eventually "roll out" after a number of starts?
Mind you, we were discussing swapping it for a CLS just before Millau so maybe it overheard!
Ahh... that'll be it then! :D
 
The codes will be stored and as you've got Mobilo you may wish to use it sooner if the problem persists.
 

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