2002 112cdi p1221 error fix? - Mercedes-Benz Forum
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post #1 of 4 (permalink) Old 11-21-2015, 08:50 PM Thread Starter
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2002 112cdi p1221 error fix?

I have recently purchased a 112cdi. It is a great van, right up until it went into what I suspect is limp mode. It starts and stays in 2nd or 3rd gear and shows no speed. My mechanic plugged the scantool into it and it's showing a p1221 error code. Something tied in with the traction control. i previously pressed the W button and nothing seems to have happened (no change in engine or trans behaviour). I have no idea what has caused this problem and I don't want to pay for my mechanic to pour over it if I can find a solution from one of the knowledgeable guys on here! Any help is much appreciated!
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post #2 of 4 (permalink) Old 11-21-2015, 11:31 PM
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Sounds to me like your mechanic only has a simple OBD fault reader, or if he has a really decent machine he has not gone in far enough to find the root cause fault code at the bottom of this problem...........

Let me explain...........

Simple OBD readers only pull SOME emission related codes from the engine ECU, but they don't pull codes from the other ECU's like gearbox, ABS, Traction, Body Control etc. They can however pull a CAN bus code from the Engine ECU..........

P1221 is a CAN error, which in english means that one or more of the other ecu's has one or more fault codes.
These ECU's will then communicate this to each other by posting a P1221 code via the CAN bus

The engine ECU has seen this and gone into limp mode, also sounds like the gearbox ecu has gone into limp mode, or the gearbox electronics is where the fault lies.

However, if Traction or ABS was mentioned, I suspect it is one of those that is sending the CAN communication, and therefore it is probably an ABS sensor that is the most likely culprit.

What you need now is a more in depth code read with either Mercedes Star, or Snap On, Autologic or Bosch.
The latter 3 are the ones most decent independent garages will have and will give you the root cause code, which will then point you in the right direction.

Ask before you pay again whether they are able to access the other ECU's and tell them a CAN code is no use on it's own. If they look blankly at you walk away


Cheers Dave

Last edited by Dave2302; 11-21-2015 at 11:34 PM.
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post #3 of 4 (permalink) Old 11-21-2015, 11:52 PM Thread Starter
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That is great advice Dave! Thank you very much!! I will take your advice and act accordingly!
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post #4 of 4 (permalink) Old 08-05-2019, 05:01 AM
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Sorry to dig up that topic but I am not able to send pm..

By searching on google how to fix p1221 error I found your topic.

I have the same things with my clk no gear displayed, p1221 and P2211.

How did you solve that problem ?

Thank you.
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