I have a 2001 Allroad with 2.7T. I have the APR chip. I use 93 octane gas. The car has 60K miles.

Recently, on 2 occasions, when the engine was cold, the car bucked the first time I hit the gas in the morning. Each time, the problem went after the one incident (once the car is warmed up, it doesn't repeat)

I am trying to debug the problem.

When I turn the car on, the next time after one of these incidents, the check engine light comes on at ignition, and stays on. I pulled the fault codes using my VAG Tool.

Here is what I got:

17862 - Exhaust Gas Temp Sensor 1 (G235): Short to Ground
P1454 - 35-00 - -
17521 - Oxygen (Lambda) Sensor: B1 S1: Internal Resistance too High
P1113 - 35-10 - - - Intermittent

Both times, I cleared the faults with the VAG tool. Since then, I have been warming the car up a minute or two in the morning, and the problem has not repeated.

One thing I am trying to eliminate is "bad gas" - I have emptied and refilled the tank. Let's see how that goes.

Anyone have any experience with this sort ofbehavior that might have an idea what I might do next?

I had a 2000 A6 that needed new plug wires that did similar things (bucked, was misfiring), but it did it intermittently throughout a drive, and usually when wet. Because it was intermittent, it cost me a fortune to have the mechanics figure out what was wrong - all kinds of testing and trying things before they finally fixed it. I would like to go into the mechanic a little "smarter" this time, so I appreciate anyone's inpute. Or, I could fix it myself if it's just a sensor that needs replacement.

Thanks in advance

Mike F

mine went at 62,000 miles. See <a href="http://forums.audiworld.com/allroad/msgs/54005.phtml">here</a>. You can fix for much less with the same Bosch part with a VW connector. Or check into your states emissions warranty laws. Since oxygen sensor is part of the emissions system it may be covered by the dealer as part of longer emissions warranty.

I have no experience with the EGT sensor. Search the S4 forum.

This may be the problem as the APR File within the chip may be keyed to the non flashed ECU files.
The newer files from APR for 2003 ECU addressed this. Allroad ECU ending in R or S

mikef: you are not getting misfires, this may be a question for your APR installer.. you may just need to update your program. in addition, the sensors do fail. 93 octane sunonco, exxon/mobile etc. have always worked fine.

It seems to only happen when the car first starts in the morning (note here in CT we are getting cold mornings now as well).

The idea that the heating element may be crapped out is sounding possible.

Huge thanks for the DIY tip on how to replace these!

How do I know which one to replace, from the VAG diagnostic info?

Mike

the egt probe you can see sticking into exhaust manifold though heat shield if you remove maf sensor and accordian hose on left side iirc. you will be able to see o2 sensor also by removing the same parts, but that is in the downpipe after the turbo and before the pre-cat.

I was using 93 when it was bucking. I haven't had the problem since I put in the new tank of gas. Starting to think, bad gas.....