My Audi A2 1.6fsi shows fault code relating to knox and lambda sensors are the two connected in any way. Mechanic said that it was one of the lambda sensors first now he is referring to a knox sensor. I have changed all four coil packs and plugs due to previous faults and the car was ok for 3 weeks, I now have the above faults but the car runs very well, is this just due to rubbish electrics and sensors because fault lights have been on more than off over the past four years.

Oxygen sensors codes are notorious for creating codes when the problem is really in the electrical firing system.

I would check the plugs, wiring, and coI'll packs 1st

p0131 is a lambda sensor fault bank 1 or could just be a exhaust leak you should go to a good reliable mechanic for help

Probably a lambda sensor faulty! Get the fault codes read to know for sure.

1-2-2 means the sensor in the air inlet duct is disconnected or open.
2-3-1 and 2-3-2 means your o2 sensor has probably failed or possibly is related to the first. If the air sensor fails on a Regina system (square ignition coil on driver's side) then the system, being as dumb as it is, will attempt to put a constant integer in there, computing solely on MAP readings and probably guessing poorly on what the A/F mixture should be. So fix the air sensor first, reset the system, either by disconnecting the battery negative cable and waiting 10 minutes or clearing the codes out by hand.

As it says just one bank I would suspect possibly an injector or lambda. In Vagcom you can do a lambda load test, I suggest you do this as it individually does each lambda sensor to check it.

Check your injectors as well.

Hope this helps; also keep in mind that your feedback is important and I'll appreciate your time and consideration if you leave some testimonial comment about this answer.

Hello!
The codes stand for the second lambda sensor and the secondary air injection solenoide. Check if you have 12V supply voltage at the lambda sensor.If you have it then probably the sensor is damaged, if you don't you have to check the fuses and wires.

BMW outputs codes in Hex format. The tool then reads the code and it may translate it to its own format. Some 29A.. code definitions here:

29A0 Lambda Sensor Post Cat Bank 2 Signal
29A1 Lambda Sensor Post Cat Bank 2 Signal
29A2 Lambda Sensor Pre Cat Bank 2 Signal
29A3 Lambda Sensor Pre Cat Bank 2 Signal
29A4 Lambda Sensor Heater Pre Cat Bank 1 Activation
29A5 Lambda Sensor Heater Pre Cat Bank 2 Activation
29A6 Lambda Sensor Pre Cat Bank 1 Signal
29A7 Lambda Sensor Pre Cat Bank 1 Signal
29A8 Power Management Network Failure
29A9 Power Management Battery
29AB Torque Request via CAN
29AE Tank Cap

Code 29A8 it's a NETWORK management fault, related with tne main computer. Will need to visit BMW dealer to delete or reset it.

I hope helps with this.

BMW outputs codes in Hex format. The tool then reads the code and it may translate it to its own format. Some 29A.. code definitions here:

29A0 Lambda Sensor Post Cat Bank 2 Signal
29A1 Lambda Sensor Post Cat Bank 2 Signal
29A2 Lambda Sensor Pre Cat Bank 2 Signal
29A3 Lambda Sensor Pre Cat Bank 2 Signal
29A4 Lambda Sensor Heater Pre Cat Bank 1 Activation
29A5 Lambda Sensor Heater Pre Cat Bank 2 Activation
29A6 Lambda Sensor Pre Cat Bank 1 Signal
29A7 Lambda Sensor Pre Cat Bank 1 Signal
29A8 Power Management Network Failure
29A9 Power Management Battery
29AB Torque Request via CAN
29AE Tank Cap

Code 29A8 it's a NETWORK management fault, related with tne main computer. Will need to visit BMW dealer to delete or reset it.

I hope helps with this.

The check engine light comes on for various reason, for example an emissions related problem (gas cap left off) to sensor malfiunction....the difficult thing to do is to diagnose it without knowing further info

However, every time the check engine light comes on, it registers a fault, trouble, code that provides an idea of what system may be at fault and thereby increasing the likelihood of tracing the problem......if you got to a local mechanic and get him to connect a scan tool, this will provide you with this trouble code......let us know how you go

the mechanic sounds like he jerks too