Dave4roma

I have some info about the CEL light problem P1113, P1114, P1131, P1140: B1S1 Internal Resistance Too High-- Intermittent same for B1S2, B2S1, B2S2.

Usually occurs along with P1411 and P1423, others referencing Sec Air Injection Flow Too Low (Smog pump).

I have replaced many sensors on this vehicle my self. The dealer costs were just too high. But this code stumped me. I replaced the oxygen sensors with parts from the internet that said they were compatible with my 2.7T.

First I got the DIY style with butt crimp connectors. I thought 'internal resistance too high' meant I had a circuit problem. Next I tried ordering the sensors with the connectors attached. After replacement I was all excited to have finally solved it. I drove about 2 days and CEL came back.

After much pulling of hair, I found the 2.7Biturbo-SelfStudy.pdf document online. I highly suggest obtaining it by search engine.

On page 52, it talks about the innovation on the 2.7T engine of the Lambda probes G39 and G108. The new improved Lambda Probe is not your Daddy's O2 sensor. I quote the guide:

'To ensure that the exhaust gases are treated efficiently, it is important that the lambda probe should react quickly... The probe heater isd integrated in the sensor element. It quickly reaches its operating temperature...The lambda control is ready to operate approx 10 seconds after engine start-up.'

One of the key characteristics of this special O2 sensor is the internal resistance. If you use Vag-Com engine measurement blocks to check measurement groups 31-49, you will find a wealth of info. One of those groups shows B1S1 resistance -- heater on/off -- B1S2 resistance -- heater on/off. The default value is 0.0 to 0.5 kOhms. If you run your RPMs to 1800 for about 10 seconds, a working O2 sensor will drop the resistance to at least 0.5 kohms and Vag-Com will show you.

I checked my brand new sensors off the internet and they showed 2.5 kohms to start and it took running about 2 minutes at 2200 rpm before they dropped to 0.5 kohms. It was enough to pass the readiness code, but not a fast response at all.

If the ECU calculated the O2 sensor resistance, it will be way off and throw a code. When the engine is cold and just starts up, the Sec Air Injection (smog pump) turns on and pumps cold air into the exhaust. This allows the catalysts to burn hotter with pure Oxygen feeding them, and quickly warms up the catalytic converter.

If the O2 sensor is not to operating temp in the first 10 sec, the ECU will use the cold O2 sensor value to run its check on the Sec Air system. It of course will be wrong and throw a code.

The only remedy to this is to pony up for the high performance Bosch sensors. I found ones with connectors to the right length for $125 on various internet parts stores. I also found the DIY with screw-type splices in a fancy connector for $65 each.

So, if you start from scratch and buy the right Lambda Probe, it would cost you $260 minimum to replace all four. If you try to cheap out, it will cost much more in parts and much frustration in labor and trouble shooting.

Also, slow responding O2 sensors will screw up the ECU's calculation of the warm-up catalyst efficiency, and might also cause other OBD2 codes relating to exhaust. On a car over 100k, I would start with fresh O2 sensors (Bosch only) before believing those other codes.

Edd W

Good post and I am surprised no-one else has yet picked up on this.

2.7Lturbo

not to be a dick, but i though this was common knowledge on these cars? the entire fuel circut on this car is wicked high tech

Ultimate Luxury

So Dave4roma, where did you buy your O2 sensors? Any chance you might provide a link? I have the exact problem and am trying to find the best price I can. I am a real cheapskate, and will be installing the B1S2 replacement myself.

socalclimber

O2 sensors are not a part you can skimp for the stated reasons, go Bosch OEM only. AutohausAZ seems to have good prices, 2000 A6 2.7 shown here:

http://www.autohausaz.com/search/pro...@Oxygen Sensor

That's where I'm getting mine when I get to 100k miles or thereabouts.

rossej

I got mine O2 sensors at Amazon.com. My sensors were for a 2.8L and were the best price I could find on the internet. Find the correct Bosch part numbers for your car and do a search on their website.

68jcode

Looking for some help on this very subject, my post is here:

https://www.audiworld.com/forums/sho....php?t=2801377

I had not found this post until now. I used the high quality Bosch O2 sensors and am now receiving the same code:

P1131 - Oxygen (Lambda) Sensor; B2 S1: Internal Resistance too High

Have you guys been able to resolve this? The guidance I received so far is to switch the O2's from pass to driver etc to see if the problem moves with the sensor, which would indicate a defective sensor. So I will do this on Saturday but would rather not waste time if there is something else at cause that you may have determined. Appreciate your responses.

spoon2000

I agree with ordering only Bosch O2 sensors, but I disagree that they have to be the OEM equivalent ones. The only difference between the OEM equivalent sensors and the generic ones is that the OEM equivalent sensors have the Audi harness plug pre-wired onto them, whereas the generic ones require you to splice the wires and to reuse the plug off your malfunctioning O2 sensor (the splice kit and easy instructions are included). I installed the generic version and it has been working flawlessly.

If cost is more important to you than job time, and aren't a complete car repair novice, go with the generic "universal fit" ones and you'll save about 50% on the part. FWIW you will probably need Bosch sensor 15733 (confirm this, obviously) and you will almost certainly need an oxygen sensor socket kit (you can borrow them from many auto parts stores).

Bosch part finder:http://www.boschautoparts.com/Vehicl...artFinder.aspx