My car has been throwing a p0402 code almost since a bought it! I've taken it back the dealer/salesman several times and the code is always a p0402. The error code is something like a 'bank 1 less than optimal efficiency'. The guy tells me that we need to replace the o2 sensor.

So, today (sat, 3/6) we replaced the o2 sensor. a little later in the evening the light pops back on. Any thoughts or experience on this?

Just to make things interesting - this 1.8t takes a 5 wire o2 sensor - even though all of the parts people tell me that the 2001 should be taking a 4 wire o2 sensor.

Hmmmm - could it be that the previous owner (not the dealer/sales) put on the wrong o2 sensor??

does anyone know if the 4wire o2 sensor and the 5wire o2 sensor (from the '02's) both use the same connector?

Any help, information, support would be appreciated.

I bought this Audi thinking it would be reliable and give me peace of mind. The car has been nice and rather fun to drive (and handled great in the snow) - but the CEL errors (and one day of misfires that were promptly rectified by cleaning the plugs) have given me anything BUT peace of mind.

Thanks!

 

P0410 is related to the secondary air injection system, not the oxygen sensors. There should be a vacuum line from the airbox to the sec air pump - check that it is connected and not cracked. At cold start, do you hear a shop-vac suction noise until the RPM drop to idle speed? If so, your pump is on its way out. If not, it's probably a relay or vacuum line leak related to the air system.