After a battery replacement the check engine light came on, with an error P1857 (Manufacturer Control Transmission). Car shifts strange and feels very sluggish, almost as if it is stuck in the second gear. Resetting the codes does nothing.

Can someone tell me how to go about fixing this, where is the control mechanism located so that I can locate it on the engine. Any help is appreciated.

 

Hi. This one stumps me too. Did the CEL come on just after changing the battery or was there some time delay? If it came up right after installing the new battery, I would start diagnosing it with the simple things first. Check the terminals and be sure their tight, and then test the battery with a voltmeter to ensure its fully charged...And not to insult you if you installed the battery yourself, but did you "Arch" the battery as it was being put in?

 

The batter is fully charged. The replacement was simple and there was nothing unusual about it. Before, I got the batter (while running the old one) I had to have the car jump started. The code came up after the batter replacement. I did check the terminals and they are tight. I reset the code again and now it just runs even worse.

The car run fine before, but it always had P0102 (MAF or VAF code). I don't think that this could be it as that code seems to be a permanent thing and did not cause the CEL to come on. Where is the throttle conlorer on A6? I could not find it and I don't have any manuals. I did a quick look at the engine block and all wire seem to be in just fine.

1) could this be a computer issue?
2) could this be a sensor issue?
3) could this be a thottle control issue? (where does it come off from the engine block/computer)?

Few months ago I replaced the purge valve and the code reset went smothely (again P0102) was there as well.

4) If I take it to the dealer, what should I tell them so that they don't take me for a ride?

Thanks for your help

 

P1857

Load Signal Error Message from Engine Contr.


According to Bentley web site the P1857 code is as shown above. I have my Bentley manual on my home computersoI can't tell you what it says about fixing the problem.

 

bump

I am giving up and will go to the mechanic tomorrow But still if anyone has any idea, then please let me know as it will make assessing mechanic's diagnosis easier.

 

it's in your ecu(computer). you will probably have to have them rest your computer. simple fix i think.

 

So how is it different than resetting the codes using the Code Scanner?

Apparently, my experiance is not isolated as I found others posting a similiar behavior and same error code after their battery was replaced. Unfortunatelly, answers on how to fix this problem are all over the place and do not converge on anything specific. This makes me think that it may be a computer related issue. What worries me is that I did reset the codes and the thing keeps comming back.

 

Hi again. I read in your post that you don't have any manuals for your car. Have you checked under the steering column? My A6 manuals were in a slot here and not in the glovebox.

 

Yes, I checked under the column. Took it to the mechanic. Two hours of his labor and he reset all of the computers, etc. The CEL is off but the car does not drive as it did before. Hopefully it just needs to recalibrate and will get back to the previous performance level.

Anyway, word of advise. Don't touch this car, sell it if you own it. Replacing a battery could cost you more than you expected. Somehow it is amazing that the car computer can't hold enough backup elictricity for two minute battery replacement.

 

how is the car driving now