ECU Gearbox Fault code U1209 (DS3 Citroen) Auto & Limp mode

[hanszuko]

Hello, I have a 2019 308 diesel AT, with the EAT8 gearbox. For a few days, he was left without DRIVE, he only placed NEUTRAL or REVERSE. I put DRIVE on and the dashboard shows "Sport and Snow" and it doesn't move forward. The scanner only returns U1209.
Any ideas?

[tricoloured]

Hi

I had the same U1209 code on my 2018 Peugeot Expert with the EAT6 box shortly after i got it (September 22), I initially thought it was a wiring loom fault as when the loom was moved the fault cleared but it turned out to be the plug into the gearbox ECU that was loose, the little barb that holds the plug in place was somehow too short, possibly damaged when the new ECU was fitted, I put a thin cable tie around the plug and ECU and it has been fine since, fingers crossed.

It had been fitted with a new gearbox ECU by a main dealer only a couple of weeks before I bought the van, there have been other issues since then that I suspect were down to the same main dealer.

Cheers

[hanszuko]

OK thanks.
I disassembled the gearbox ECU, everything seems to be normal, I'll look at the pins now.

[tricoloured]

Hi

That looks totally different to the unit on my van.

I know many faults can result in the U1209 fault code including the brake light switch as was mentioned earlier in this thread, are you using Lexia/Diagbox as some but not all scanners will show the info needed past the initial fault code.

Cheers

[GiveMeABreak]

Your're talking apples and pears gentlemen....

hanszuko has an EAT8 gearbox and tricloured is talking about an EAT6

[tricoloured]

Hi Marc

I was aware of that hence why I mentioned it in my initial post, as the U1209 refers to a comms issue I thought it was worth a mention particularly the brake light switch as this has been an issue often missed on many models.

Cheers

Bobby

[GiveMeABreak]

No worries, just didn't want you to go off on tangents thinking you were talking about the same box. I don't always have the time to read through all the preceding posts when I'm working Forum-wide

[hanszuko]

Hello, I couldn't find anything abnormal on the pins of the gearbox Ecu. About the brake switch, if the rear brake light works well, could it be bad?

Thanks !

[hanszuko]

Hello, here are the scan results (Not Alexia).

Errors before cleaning:

Errors after cleaning (Permanent):

[LEOAKIE12]

Hello Please update solution i have same issue

[LEOAKIE12]

Hello I hope.you find the issue and got it fixed can you share update i have same problem thank you

[Paul-R]

hanszuko hasn't been back to the site for over 2 years now. His last visit was on Tue Apr 2, 2024 so you may not get a reply.