722.6 gearbox - Harsh first gear change during this hot weather

AnthonyUK

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My old C240 is suffering a bit in this hot weather.
The gearbox has been pretty much perfect but when the outside temps get to around 30ºc, the first gear change up and also when coming to a stop are quite harsh.
The gearbox filter and fluid were changed about a year ago so any ideas what could be the cause?
I'll find a flat surface and check the fluid level shortly too.
 

V6Matty

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Complete guess here but it could be the level is just a tiny bit high, probably no issue most of the time but as it’s so hot it’s just expanding that little bit
 

Jim2

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For the 722.6 trans, 80c is the correct temp to check the level, making sure that the car itself is also sitting level. I'd suggest checking it early morning. If it shows correctly at the 80c mark, then it is something else that's causing the harshness.
 
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AnthonyUK

AnthonyUK

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Thanks.
I think there is something more amiss as I can only intermittently read the codes and my i980 is unable to clear them or read live data.
I think I’ll also check the connector housing as I have a spare if it needs it.

There is a stored code of P2001.
 

Jim2

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Thanks.
I think there is something more amiss as I can only intermittently read the codes and my i980 is unable to clear them or read live data.
I think I’ll also check the connector housing as I have a spare if it needs it.

There is a stored code of P2001.
A quick google search ( Mercedes Benz fault codes) gives the following info:

Quote :- The P2001 code usually indicates that the powertrain control module (PCM) has detected a level of nitric oxide (referred to here as NOx), as reported by the post-catalyst NOx sensor, that is higher than desired. Bank 2 refers to the side of the engine not containing the number one cylinder.7 Jun 2016 UnQuote.
Could this be the cause of the cars behaviour?

As for the electrical connector, have you ever changed one before? I know that a lot of people change them to prevent wicking ( where the ATF fluid finds its way up via the wiring to the ECU, and causes problems ) If you are changing it, be carefull as there are (I think )13 fine pin connectors involved, and its very easy to bend or dislocate one or more of them.
 
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AnthonyUK

AnthonyUK

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A quick google search ( Mercedes Benz fault codes) gives the following info:

Quote :- The P2001 code usually indicates that the powertrain control module (PCM) has detected a level of nitric oxide (referred to here as NOx), as reported by the post-catalyst NOx sensor, that is higher than desired. Bank 2 refers to the side of the engine not containing the number one cylinder.7 Jun 2016 UnQuote.
Could this be the cause of the cars behaviour?

As for the electrical connector, have you ever changed one before? I know that a lot of people change them to prevent wicking ( where the ATF fluid finds its way up via the wiring to the ECU, and causes problems ) If you are changing it, be carefull as there are (I think )13 fine pin connectors involved, and its very easy to bend or dislocate one or more of them.
Are you looking at the same error code?

My reader gives P 2001 Component N15/3 (ETC EGS) control unit is defective.

I’m an ex-avionics engineer so actually happier with the electrical side of things. It’s the rest of it I struggle with
 
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Jim2

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Are you looking at the same error code?

My reader gives P 2001 Component N15/3 (ETC EGS) control unit is defective.

I’m an ex-avionics engineer so actually happier with the electrical side of things. It’s the rest of it I struggle with
I did a google search "Mercedes Benz Fault code P2001", and the result I copy-pasted in my reply to you. But I'd say that of the two code interpretations your one is correct, and it actually refers to the conductor plate when you google " N15/3 (ETC EGS) control unit ", So this could well be your problem.
Normally when I am replying to posters who are looking for help / advice on a problem that they have, unless they say in their post what experience they have, I'm not aware, so I try to warn of any pitfalls. And when I tried to to replace the connector in my first MB ( 2010 Eclass 200 with the 722.6 trans) thats exactly what happened...I bent one of the pins. Bearing in mind that it did not need replacing at that point, but I was being extra carefull in preventative maintenance :geek: Now if I were doing it again.....I'd have done it while I had the sump down. But you live and learn. With your experience in avionics, replacing the conductor plate ( and socket ) will be a doodle.Best of luck with it and let us know how it goes.,
 

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