Muggsy2006

I have been driving my 2014 S4 for 2.5 years and love it, but this is my first real issue with the car. Back at the end of March 2016, the check engine light came on for the first time, at roughly 28000 miles. Brought it to the dealer for service and they replaced an oxygen sensor. Six weeks later, the light came back on, brought it back to the dealer and they replaced the other oxygen sensor. Got the car back a couple of weeks ago, drove it less than 100 miles and the light came back on.

My car has been at the dealer for a week now. They called me on Friday and said the mechanic found an issue with the catalytic converter, which they will be replacing. Seems way early for that type of problem, but I'm going with it. Ironically, that night I was talking to a friend who has a 2012 S5 with 70K miles, and he has had the exact same issue with his car, except he's been dealing with it for many months now. He has been through all the same steps they're doing with mine, except nothing has worked. Now I'm a bit worried. I have a year left on my lease, and was planning to buy the car outright, but it this is going to be a recurring issue after the warranty expires, I may have to rethink it.

One other point, each time I they replaced an oxygen sensor I had to leave the car at the dealer overnight, because they had to order the part. Service advisor told me they rarely keep parts for S models in stock, like they're some rare bird you never see on the road. I find that pretty ridiculous, it's not an R8. I have owned 2 M3s, and replaced multiple oxygen sensors in both cars, but BMW always had them in stock. Have other S4 owners had a similar experience?

bhvrdr

Without posting the code its hard for any of us to give advice. Emissions related codes can often signs of several different parts failing and the audi computer literally tells the audi techs which parts to replace first (the most likely to fix the problem and least costly solution). Many times you can get similar codes for failed coilpacks, o2 sensors, fuel injectors and catalytic converters. It happens.

That said, the B8 S4 seems to be one of the more reliable platforms audi has had out for quite some time. Out of warranty, I would be most worried about DSG transmissions and sport diff failures. If a 5K to 10K parts failure would significantly matter to you I would look at trading the car out of warranty.

Mike

Muggsy2006

Thanks Mike. If it helps, here is the code info from the first three repair tickets.

3/31/16: Found fault code P2272, o2 sensor signal stuck lean Bank 2 Sensor 2. Ran test plan and found rear oxygen sensor for Bank 2 was faulty with false lean values. R&I and replaced Bank 2 Sensor 2 oxygen sensor (after CAT).

5/27/16: Found fault code P2272, o2 sensor signal stuck lean Bank 2 Sensor 1. And P2273 o2 sensor signal stuck rich Bank 2 Sensor 1. Previously rear o2 sensor was replaced. Readings were plausible from rear o2 sensor but noticed front o2 sensor for Bank 2 would throw an incorrect reading intermittently. R&I and replaced Bank 2 Sensor 1 pre-CAT oxygen sensor.

6/14/16: Found fault code P2272 Bank 2 sensor oxygen sensor signal - stuck lean. Due to re-occurring issue, contacted TAC. Advised to perform specified/actual, check o2 sensor wiring, and perform inspection of catalytic converter. Performed specified/actual, no actions needed. Checked wiring for heater circuit of oxygen sensor and Pins 2, 3 and 4 to ECM. All within spec. R&I transmission and removed left catalytic converter. Performed inspection of CAT element inside, found honeycomb element for catalytic converter to be coming apart causing lean readings for rear oxygen sensor. Replaced left catalytic converter.

bhvrdr

Right on. yes it looks like they did pretty much what any mechanic would have done. They started with the o2 sensor, which could have been the issue, and then on to the cat converter which would have been a much more costly repair. I believe the cat converter is also covered under federal emissions 8 year/80k mile warranty as well (check me on that one) so that may give piece of mind. Hopefully no more issues for you. Like I said though, you do have 2 very expensive parts on your car...the DSG and the sports diff. If your car was a 6mt with standard diff i'd say keep it out of warranty. Best of luck.

mike

jyges

I believe 8/ year 80K warranty on cat converter and related equipment

PhilNotHill

Might want to check your state's lemon law.