Hi, can anyone give me a steer to sort out a auto box fault on my 2001 W203 220CDI auto?

Its been acting up for a bit, refusing to change up when starting from cold, I just drive a few yards down the road and realise that it wont change up- when i pull over and switch the car off and back on again it works fine!! it only seems to do it on the really cold mornings we had recently. Its not done it for a while but the fault may be linked to its latest attempt to empty my wallet.

It now refuses to kick down at all and is only giving me about half engine power. If i try to shift manually it wont go over about 2500 rpm. It is not showing any errors on the dash so i dont know what part needs hitting.

I seem to remember it doing somthing similar about a year ago. I had a look under the bonnet and found a vac pipe had become detached from some sort of valve/sensor tucked down between the air filter and the back of the O/S headlamp. I reconected the vac pipe and it ran fine unill recently. I have had another look down there and it all seems to be connected properly. Any ideas? Thanks

 

Hi,

I had the same issue, turned out I had a leaky plug on my gearbox, have you looked under the car for any signs of leaks? It's worth undoing the bottom cover to see the gearbox sump... I've changed the plug and while I was at it drained the ATF and changed the filter, gearshifting is sooo smooth I wish I'd done this ages ago!

 

HST, do you have a picuture of "gearbox sump" where the plug might be located?
I have a problem with small amount of oil leaking which lead to bad O2 sensor(small amount of oil getting to O2 sensor socket and ruining O2 sensor-Pre catalytic O2).
If you do have a picture of "gearbox sump" plug or the description of location I would really appreciate it.
Thanks and have a great day.

 

There are often trasmission faults on this cars, especially 1999 - 2001. But, try to look for some leaks, if you can't find any, try to simply refill it.

 

High had similar on c class semi auto after merc replacing pumps etc on the gearbox turned out to be airflow mass meter wasn't working out rite mixture etc to give message to gearbox to change cost of airflow meter 60 pumps etc and labour from merc 2500 go for airflow meter first lol