Hoping someone can help me with this problem

[gazzz]

I have a 203 C200 CDI auto which has started to play up for the first couple of minutes after starting from cold.

The car starts absolutely fine, goes into drive OK and pulls away as expected except that gear changes are a bit little jerky as you accelerate - not noisy just a bit harsh and sudden in the changes and this is with fairly gentle acceleration. A particular problem is if you slow down or coast down an incline then the box changes up to a higher gear than I feel it ought to then when you gently accelerate again the car sort of surges like the gear change is partially switching up then down and the revs pulse a few hundred rpm up and down too. Same behaviour if I switch it to semi auto and being in comfort or sport make no difference either.

The colder the outside air temperature the more noticeable the problem is though it is still there in mild weather too.

What's really odd is that once the car has done 2 miles or travelled for 5 minutes the problem completely goes away and changes are silky smooth from then on.

Starting from a warm start there's no sign of it either.

I've had it at a Merc specialist twice now and they are stumped. No faults showing on Star. ATM fluid is at the right level and was changed about 10 months ago which was several months before the problem started.

Any ideas? It isn't a terrible fault but it is impacting my enjoyment of the car and in the back of my mind I'm wondering if this is the sign of something seriously wrong.

Thanks.

 

[BlackC55]

I had a similar problem with My C43 and a new temp sensor in the 'box cured it. It is part of the electrical plate and is £176+vat for the part

 

[Stratman]

when you gently accelerate again the car sort of surges like the gear change is partially switching up then down and the revs pulse a few hundred rpm up and down too.

Mine does exactly the same, but only by the width of the tacho needle and only when the weather is cold and damp.

I'll be booking a B service with Olly very soon. Let's see what he can find.

 

[gazzz]

I had a similar problem with My C43 and a new temp sensor in the 'box cured it.

Thanks for the advice. Would that not show up on Star then? If I tell the garage what you think the problem might be will it be obvious what the part is that needs to be replaced? What is it that the sensor does?

In the meantime will it do any harm to drive the car until it is done?

Mine does exactly the same, but only by the width of the tacho needle . . . .

That's interesting. I wonder if I just missed it when it wasn't that bad but it has got worse over time?