Traction Control and ABS light ON, and DTC codes 18034 & 17861

**Gigi** · 07-09-2008 10:41 PM

I was wondering if any of you had experienced the following and/or knew what the causes might be.

1- NO CEL light.
2- Car runs normal, no issues with shifting nor acceleration... NO limp mode nor misfires.... Would not know there is a potential issue if not for the following...
3- Only noticeable issue is that when you turn the key to the ON position and without starting the car [usually wait a couple of seconds, lights on the dash usually come off.... then start the car] sometimes the ABS and Traction Control lights stay on and would stay on even if you start the car.
4- So once the key is on the ON position, IF the ABS and TC lights stay on, instead of starting the car, you turn the key back to OFF. THen turn it to ON again, wait a couple of seconds and the ABS and TC lights go off as they should. Always works fine the second time.

So anyway, it's been doing this for a month + maybe but was not a big concern because the car runs great and NO CEL. Even without a cell, VAG revealed the following codes while ON with the traction & ABS lights on:
Two codes came up, though one is most likely unrelated to the above:

- Code 1, most likely related to above issue:
DTC 18034 Data-Bus Powertrain missing message from Transmission Control (Sporadic) (P1626)

- Code 2, unexpected and have no clue what it is since there is NO cel lights and engine runs fine. Boost leak? EGT sensor.... whatever they are, temp sensors?
DTC 17861 Exhaust Gas Temperature Sensor 1 - G235: Open/Short to B+ (Sporadic) (P 1453)

I did search but did not find the same type of issues. I did find a few posts where some members had these DTC codes but combined with amany others and other obvious symptons such limp mode, car running poorly, misfires,...
I appreciate any help you can provide.
Thanks in advance.

**PMR2.7t** · 07-09-2008 10:47 PM

Traction Control and ABS light ON, was on in my car and it was a bad brake switch..

**Gigi** · 07-09-2008 10:55 PM

^ interesting! I chnaged the switch just a few months back....
MY symptoms were different though. My brake/tail lights would stay on when I turned the car off, rear brake lgith would not work unless braking real hard and car would stop accelerating period with no warnings :) $4 switch resolved the issue! AUDIs... rrr!

**FrankA6** · 07-09-2008 11:00 PM

Yo Gigi, our other A6 had, and has been now for a while had the ABS and CEL on, and they brakes shake real bad when they come on, its really wierd, but it sounds like you just have a little stupid problem, im sure its nothing. atleast it sounds that way, if the car is running and working fine.

**skiroad'r** · 07-10-2008 06:40 AM

Second the brake switch theory, even though you recently replaced it. Double check the install/connections? This was the common cause of the "Chistmas Tree" of dash lights you describe.

**A62TURBO** · 07-10-2008 10:37 AM

DTC 17861 Exhaust Gas Temperature Sensor 1 - G235: Open/Short to B+ (Sporadic) (P 1453) means you have to change the ex. temp sensor in your manifold, as for the other code I have no clue.

**Gigi** · 07-10-2008 12:01 PM

Yeah i am talking to VAST about the EGT, they sell them. I also aksed them abuot the other tranny code.
I might pul the TCU out tonight to make sure it is dry, the connections are clear and the chip is firmly planted in the socket.... just in case.... but my problem is so sporadic I would think I'd have other more consistent symptoms if the TCU had an issue.????
Freakin' Audis!!!
I am sure it is probably nothin and I don't even have a cel but I will get to the bottom of it. Especially as I am considering selling it soon... Will be at the shop Monday anyways to get my wheels back on and change fr brakes. but I like to know what the problem is before going to the shop...

**A62TURBO** · 07-10-2008 04:14 PM

Check ECS for ex. temp sensor as well, ive seen it on there.

**2sl0** · 07-12-2008 04:09 PM

i have kind of the same problem with the traction control and ABS light being on. at first it would come on and go away, but now its on all the time. i took it to my mechanic and he told me it was a pass side speed sensor. would be covered on my warrenty but ofcourse my warrenty company went broke so now im gona end up paying for it.