2002 w203 C220 CDi transmission flaring

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New Member
Dec 8, 2011
C220 CDi
Hi all - I wonder if anyone can help.

Bought the car only a couple of months ago, my first auto, I think the problem has been with the car since I had it (cheers seller :mad:).

The gearbox 'flares' - kinda slips, only between 3rd and 4th and only when it's warmed up 10 miles+

I've just shelled a good bit out on a pal changing the conductor plate, filter and ATF... all to no avail :doh:

The only other scenario/solution I've had put to me is the leaking radiator, coolant problem - and the cost £2000, can't warrant spending that, and that problem seems to present itself differently.

I've not checked the (passenger in uk?) footwell to see if TCU has been affected by the 'wicking' problem - but the plug showed no signs of leaking.

Any other ideas? low pressure? k3 clutch? solenoids?

Meant to say, fault codes retrieved ...

P2602 The voltage supply to the valves is faulty
P2600 The voltage supply circuit 87 has under voltage
P2500 The transmission had an impermissible transmission ratio
P2001 Component N15/3 (etc) control module is faulty.
Firstly, forget the radiator, it is not used for transmission cooling on your model.

The fault codes.
You have a few to look at there, the P2602 (and P2600) suggest the car has had a battery issue (possibly allowed to go flat, possibly just beyond servicable condition) at some point, but if current the P2602 code would stop the gearbox from changing up. You do not mention this, so I will assume it is an historic code, with no relevence at this stage.
The P2001 code could be logged in many ways, and is often spurious and undiagnostic, if it fails to return disregard it.
The P2500 code will be generated by the 'flaring', and will likely be the only one to come back after erasing. Sadly it is not very helpful in pinning down the actual cause of the slipping though!

My first guess is valve body wear, that is known to give your symptoms exactly (slipping between 3rd and 4th when at operating temp). An exchange valve body is approx £500 from MB, but the transmission specialists can repair them for much less.

Have a look here, kit no.10 http://www.sonnax.com/downloads/valve-body-layouts/VBL-Mercedes-722-6.pdf

The above advice assumes that no debris was noted during the electroplate change, and that the fluid level is correct.
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Thanks Alex, that helps narrow things down - especially keen to disregard rad fault.

I'm going to have a look at TCU over weekend (wicking), but you don't seem to think that's involved, so that's fine. I haven't had chance to get codes read again since clearing, so not sure which are still current, will get them ASAP.

Which suppler in UK would you recommend for the sonnax kits?

Thanks again
Looking at jigs etc perhaps the Sonnax kit repair isn't for the humble DIY'er?

Anyone recommend where to get the valve body refurbished?

Looking at jigs etc perhaps the Sonnax kit repair isn't for the humble DIY'er?

Anyone recommend where to get the valve body refurbished?


I got my valve body refurbished at Robb's Garage. They have the equipment to test and repair mercedes valve bodies.

Robbs Garage

I took mine out and they have an account with a courier who picks it up from you and drops it back. Very quick turn around.

It cost me around £300 but I was only getting the lockup valve rebored.

I would give them a call.

They were very helpful and knowledgeable.

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