o2 sensor help
 

Hope some of you can add some comments. I'm tired of dumping cash into my car, and want some re-assurance from you experts.

I replaced B1S1 2 months ago, and the code quickly came back up. There was another code that my indy dealer could not read, so I broke down and took it to the audi dealer for a diagnostic. I gave them some business, but they told me the two 17... codes were related to a bad o2 sensor and a bad cat converter. What are the odds that this sensor is already bad, + now code 16518 appeared. Is there anything else that could be causing these codes besides a bad 02 sensor and a bad cat?

I found some paperwork with this car that looks like this sensor was replaced last year as well - previous owner. Could a bad cat be making these sensors go bad?

16518 P0134 O2 Sensor Circ.,Bank1-Sensor1 No Activity Detected
17521 P1113 Bank1-Sensor1 Internal Resistance too High
17866 P1458 Exhaust gas temperature sensor 2 short to ground

2001 A6 2.7t

I don't know...but I'm still getting O2 codes after swapping the pre-cat O2's twice! I bought mine on eBay....maybe that's the problem.
where did you get your O2's?

I have never seen a no activity detected code for an O2 sensor, are you sure they connected the electrical connector correctly?

The EGT (exhaust gas temp) sensor can cause all sorts of performance issues, how did you break down?

You don't need a cat converter, thats a retarded claim.

I have no idea if they connected it properly, it was done by an indy mechanic with not alot experience with audis. He's a friend, so I can ask him anything...is that what I should ask...did he connect it properly? If he didn't, either did the previous mechanic. Could there be an underlying problem with the electical system? The car seems to idle a little rough compared to how it used to, something is not right, but I hate to put money into replacing the cat unless it will fix the problem. Would an emissions test tell me if there is a problem with the cat...would be much cheaper than a replacement.

If the cat was bad enough to cause the engine to run abnormaly it would throw a cat efficiency below threshold fault. The rear O2 sensors determine if the cats are bad so thats how i know you still have a good cat because that sensor isn't malfunctiong. Your before cat O2 sensor is the one that has fault codes and thats the one that tells the ECM how rich/lean the engine is running. I would have your buddy look at the sensor very closely, the connector is right next to 3 other ones located on the firewall directly behind the motor. If one of the connectors is missing from the bundle then he didn't plug it in. If it is plugged in i would replace the EGT sensor.

Oh and just for future reference, your buddy does know bank 1 is the passenger's side and bank 2 is the driver's right? If he has been replacing the wrong bank this whole time that could also have been the problem.

I installed 2 pairs of pre-cat sensors and both times I get "no activity detected" codes. I know I've plugged them in correctly.....do i need to push in really hard on the connectors? Also, these ebay ones didn't look like the OEM ones that came out of the car...could that be the problem?
If not, where is this EGT sensor located and how hard is it to replace?

I have heard countless problems with Ebay O2 sensors, people PM me about it all the time. Don't waste your money on electronics from Ebay, buy them from either www.ecstuning.com or www.purems.com.

Madridlover, i believe you have a 2.8L which doesn't have EGT's, the 2.7T does.

Cool, thanks. I guess I'll have to break down and buy a pair of sensors for $100/piece :(

I replaced the o2 sensor and yes it was another bad one. That code is now gone, but now new ones popped up. I've read 16805 is the cat...any comments?

17867
16805