below effiecency on bank1 on my obd reader what would that be 2.4 v6 petrol

[scanny1]

i have just had the engine management light come up on my a4 2.4 v6 petrol .when i plug the obd its says irregular warm up on bank 1 below effiecency what would that be

[Big davy]

Could be a 02 sensor or maybe a vaccum leak, I had a fault 0171 bank 1 too lean and it turned out to be a vaccum leak, I did think it was 02 sensor at first

[scanny1]

is there a way of checking if its the catalyst or if its the lambda sensor

[Big davy]

You can look at the sensor and see if it's clean and still looking ok, I've been told there pretty sensitive tho. Mines were around about the 1 0 clock position in the engine bay,just in front of the battery

[scanny1]

The code that came up is p0421 and p0431 which is both sides of the engine saying, warm up catalyst below efficeincy .So is it the catalyst that need replacing .ive checked the 02 sensor by a multimeter and it read 13 apparently under 20 its ok

[Big davy]

I'm not 100% but I reckon your cat will be fine, I think you get a sensor before cat and after cat... Maybe one of them
There's normally guys on here that are excellent at diagnosing faults if you've got the codes

[scanny1]

yea the code is p0421 and p0431