tuccatucca

Hi Guys

Where to start - I've had this car for just over 2 years, put about 45,000km on (Imported to Canada,) and I have replaced both my EGT sensors now 3 times. Sometimes its short to plus, sometimes ground, here is the latest codes:

17862 - Exhaust Gas Temp Sensor 1 (G235): Short to Ground
P1454 - 35-10 - - - Intermittent
17865 - Exhaust Gas Temp Sensor 2 (G236): Open or Short to Plus
P1457 - 35-00 - -

And they usually die about a month or 2 apart from each other, strangely enough. My car is stock, except for Piggie Pipes, 710N diverters, and APR chip, which I usually run in 91 oct mode. I have replaced the MAF, and the front O2 sensors when I first got the car.

My question is basically, what the f--- ? what is going on with this? How many miles do you guys typicall get out of a set of EGT sensors? The car is running perfectly, then the EGT's die and I have random misfires, and the worst part is they only seem to live for about a year then they fail.

I have seen videos of S4's online etc, do your tech's see this as a re-occuring problem with the 2.7T? Like, is this remotely normal at all? I dont even drive the car hard, so I don't believe my exhaust temps are hot. I have Piggie Pipes, so no cats in the front, so really I should be roughly 100C less then whatever the stock EGT's are, according to what I've read online, and honestly its my daily driver and I baby it and do mostly highway cruising 2-3k RPM.

One thing I have done with the new sensors is wrap them in a heat deflecting tape, because I know the underhood temps on these cars are fairly high compared to most vehicles.. my theory is that some part of the sensor wire melts through the jacket and shorts either to ground or +. I'm not sure if any of you have dissasebled them or not, if you do I imagine you know what causes them to fail, and man I would sure like to know what that is!

I dont know if the failure point is in the electronic board, the wire, or in the sensor probe tip. Does anyone have the answer to that question?

Below is a a pic of what I've done - this tape wrap is 3 coats thick and is good to insulate from heat up to 1500F - what do you think about this idea? Should I be using a piece of heat deflecting loom instead or in addition? Since there is no moving parts in these I assume that the factor that kills them is heat, but maybe not.

The other alternative is I read about tuning companies coding them out of the software... does anyone have any experience with that?

I'm desperate on this issue - I can't keep replacing these every years at $500 a set!

Thanks

SloopJohnB@mac.com

Well, insanity is defined as doing the same thing over and over and expecting different results.

My take on it would be to quit wrapping the EGT sensors with non-OEM stuff and get a set with a gøod warranty. Preferably FCP Groton...lifetime warranty for about %10 extra if you install them yourself.

End of replacing them at $500 a set (at least after this one). That's if FCP Groton has them....I dunno.

2.7Lturbo

short to ground happens from time to time on my car for various sensors, not an idication they are bad? have you run any logs? other then the codes why do you thing the egts are bad? are you going way too fat ?

tuccatucca

That's actually an awesome suggestion - but I couldn't find them on the site, they have EGT's for volvo's and stuff but not the ones we need for the Audi 2.7T, weird. If I could pay 10% extra and have them lifetime warrantied that would be great, becaues they are anything but cheap.

tuccatucca

Thanks for the reply - in my experience, as soon as they start throwing codes (once a month, then once a week etc) it means they are slowly dying and about to **** the bed. If I leave it long enough, which I have to find out, they will cause misfires on that bank, and put the car into limp.

Thursday, 22 September 2011, 19:36:01

VAG-COM Version: Release 409.1-S

Control Module Part Number: 4B0 907 551 AA
Component and/or Version: 2.7l V6/5VT G01 0001
Software Coding: 06712
Work Shop Code: WSC 26130
Additional Info: WAUED64B91N047196 AUZ7Z0Y1562177

5 Faults Found:

17865 - Exhaust Gas Temp Sensor 2 (G236): Open or Short to Plus
P1457 - 35-00 - -
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 - -
16688 - Cylinder 4 Misfire Detected
P0304 - 35-00 - -
16690 - Cylinder 6 Misfire Detected
P0306 - 35-00 - -
16689 - Cylinder 5 Misfire Detected
P0305 - 35-00 - -

So sensor on Bank 2 shorts for a second, and the computer compensates by dumping fuel in, causing misfires only on cylendars on bank 2, 4/5/6. This is usually intermittent, and when I get on it for a second to pass or something, misfire.

What happens when you get the codes? do you ever go rich on your mixture or limp? do you get misfires at all?

I dont think any amount of short to ground is "normal", when I replace the sensors with new ones, they last about a year and I drive a long time with no codes whatsoever. Seems like at about the 1 year mark they start to throw codes, then misfires come after that...

I haven't always wrapped them, I just started, as I'm hoping it will maybe protect them or make them last longer but so far no luck

2.7Lturbo

lots of things can cause misfires besides fuel being dumped, log your LTFTs or pull a plug and see fi its running rich/lean on that cylinder.

"A short to ground occurs when current flow reaches ground before it is intended. This usually happens when a wire insulation is compromised allowing the bare wire to touch a ground. Since the metal body parts of the vehicle provide the ground path for most of the circuits, all the wire has to do is touch any metal part. The effect of the short to ground depends on the design of the circuit and on its location in relation to the circuit control and load."

short to ground is not good, but is not a dead on indicator of a bad part

tuccatucca

So I put in the new EGT on the passenger side, and no more short to ground code. I had cleared it, and it came back easily within a day of driving, and it monitoring it it seemed as though it was taking less and less time to come back.

I installed the new one, wrapped with the same heat protective tape, as well as an asbestos wrapped "sock" (apparently used for protecting spark plug boots on the wires) hoping that this will further insulate fragile things from heat.

After replacing the sensor car is running like normal again and no codes after about a week of driving.

Thoughts? I bet this code is going to come back again in about 7 or 8 months after barely any miles of driving, as usual ... is this common ?

tuccatucca

I had no codes on the car whatsoever - then I had a misfire on 4,5,6, went home, checked codes, and the only one was the EGT code. Replaced sensor, running fine. Same experience on the other side. Mind you, the misfires do not ALWAYS come with the short to ground / short to plus, I've only had a few misfires, and the sensors have shorted out alot, but I always replace them right away when they spit codes, because I believe eventually they will get to the point that they do cause misfires, as they have before - correct me if I'm wrong in that thinking ?

do you guys have intermittent short to ground / short to plus codes and just drive with them? with what effects?

SloopJohnB@mac.com

Did you give FCP Groton a call? Sometimes they can get stuff if not have stuff that the website doesn't show.

SloopJohnB@mac.com

Clearly not common or Audi would be drowning in warranty work.
Something is not right.