Hello I need some technical help regarding the replacement of both up-stream Lambda sensors fitted to my 2001 3.7 A8. It doesn’t look like these much room… The Audi workshop manual suggests the CAT with sensor attached needs to be removed first to replace either up-stream probe. Is this really necessary? Do I need any special tools? Reason for changing both Lambda probes, I keep getting “Internal Resistance to high” intermittently on either, bringing on dashboard engine management warning light. Thanks for any help Rgds, Lee

 

before you go tearing it apart what was the codes you got to determine which o2 sensor is bad??

 

Hi Dave,

I'm getting codes:
17539 - Oxygen (Lambda) Sensor: B2 S1: Internal Resistance too High
P1131 - 35-10 - - - Intermittent.

17521 - Oxygen (Lambda) Sensor: B1 S1: Internal Resistance too High
P1113 - 35-10 - - - Intermittent.

When looking forward under the car is B1 Left Hand and B2 Right Hand?

Thanks Lee