Ryan12345 Posted August 16, 2022 Share Posted August 16, 2022 Hi, I have high emissions on my A3, 1.6 petrol. I have done a full scan with my diagnostics and no fault codes are stored. The rear O2 sensor is at a steady 0.7V but the front sensor is around 2V. (Not sure if this is correct for a wideband sensor). Any ideas?? Bad CAT? bad front O2 sensor? Quote Link to comment Share on other sites More sharing options...
Steve Q Posted August 17, 2022 Share Posted August 17, 2022 The sensors will be cheaper than the cat. I'd start with the sensors and work from there. Quote Link to comment Share on other sites More sharing options...
Ryan12345 Posted August 17, 2022 Author Share Posted August 17, 2022 The sensor is actually more expensive than the cat being a wideband sensor! I didn't want to just keep changing parts I don't need to Quote Link to comment Share on other sites More sharing options...
cliffcoggin Posted August 17, 2022 Share Posted August 17, 2022 What makes you believe that either the sensor or the cat is defective? Have you considered that there might be a fault with the engine? Quote Link to comment Share on other sites More sharing options...
Steve Q Posted August 19, 2022 Share Posted August 19, 2022 I guess a fault within the air/fuel mixture could cause the issue. Quote Link to comment Share on other sites More sharing options...
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