Mystery ABS light + ESP light + power loss issue
 

I have a 2003 A4 Avant 3.0 V6, and the following issue happened to me once after taking the car to a car wash. I read tons of threads on car washes and everyone keeps asking me whether I "got water in the engine." Most definitely not! Furthermore, I now got the following issue two more times at random, so this is becoming a problem:

1. I start the car. The ABS and ESP lights come on.
2. When I accelerate normally, the car revs up like crazy (but no higher than ~4,000 RPM); however, it does not go above 70kph!!
3. The overall feeling is that I can no longer accelerate and that I've lost power.
4. This issue goes away and returns at random...

Can anyone please tell me what the hell is going on here? This is very frustrating! :mad:

Re: Mystery ABS light + ESP light + power loss issue
 

Um. Hello?

Re: Mystery ABS light + ESP light + power loss issue
 

You might not have gotten water in the engine but perhaps in some of the electronics...
When the ABS/ESP lights are on then the car likely goes into limp mode because it thinks the brakes aren't working properly. You're going to have to go through the brake and traction control systems to see why the warning lights are coming on. VCDS scan is the best place to start without going to a shop.

Re: Mystery ABS light + ESP light + power loss issue
 

Hey, I had the exact same problem (2002 A4 3.0 V6) the ESP light, ABS light, and CEL would all come on and if you look in the owners manual, it puts your car in whats more commonly known as "Limp Mode". This reduces your power to your vehicle, essentially its usually related to a Throttle body issue. If you plug in a scanner you will usually get a TPS (throttle position sensor) code, and on the B6 a4 your pretty well screwed and have no choice usually but to swap for another throttle body. I did this after getting a TPS code specific to voltage correlation, however it didn't fix my issue. As crazy as this may sound, check your ECU cover and box first for any cracks, turns out water was getting in my ECU box through a crack and was causing a small fault in the voltage, and it would put my car in limp mode until it dried up, did a quick fix with gorilla tape (since its still winter). Hope this helps you and anyone else, took me 2 months to find the exact source of the problem!

Cheers,

Frank

Re: Mystery ABS light + ESP light + power loss issue
 

Tim$2 ^ is on the right track

Re: Mystery ABS light + ESP light + power loss issue
 

Hi All,

I have a 2002 A4 3.0 Avante as well and just started to get the ESP light, and a few days later the ABS light come on at random, but seems to be more prominent when the ambient outdoor temp is above say 25 Celsius (bought the car used in November, so no prior warm weather info until now - May 2016 in Ontario). Had the CEL come on a few months ago, and code reader indicated it was an O2 sensor code (P1176 - Correction behind Catalyst, B1 Limit Attained) which went away after a few weeks (sensor alone was about $200, so had to wait a few week to get it to a shop, and it went away... Now CEL has come back, but haven't had a chance to plug it in to confirm if it is the O2 sensor again.).

I will have a look at the suggestions above, but is there any updated ideas on this one? Seems to be a known issue on other forums as well.

Re: Mystery ABS light + ESP light + power loss issue
 

@Phatso Sorry, man. If I were to guess before, I'd say that a cracked ECU cover is probably the culprit...though it's interesting that you bring up the O2 sensors.

Basically, my car was in such bad shape with CELs, that I just paid a "shop" to artificially change the thresholds for both, so now the CEL never comes up for either issue (though I guess I'm polluting more and the exhaust don't smell too good). The curious thing is that I never get the ESP/ABS/CEL combo anymore, even after a rigorous car wash.

Coincidence or freak occurrence? I couldn't care less. I'm gettin' a brand-new S5 in 6 months. :P

Re: Mystery ABS light + ESP light + power loss issue
 

thanks for the reply neothe1 Silly question... Where is the ECU cover? Drivers side beside the battery? If so it looks intact, and to get the cover off to have a look, it looks like you have to remove the wiper arms to be able to get at the back two torx bolts...?

Re: Mystery ABS light + ESP light + power loss issue
 

Yeah, it's kind of a hassle to get at it. Have a look at the guide here: http://www.a4mods.com/index.php?page=webcontent/pages/ecu.html

Re: Mystery ABS light + ESP light + power loss issue
 

SO it turns out it was the switch under the brake peddle that is noted in other threads. Switched it out at the beginning of August and no warning lights since. I think the switch was $40.00.