Questions and Answers

Volkswagen Passat DTC P0431 Q. Hello Sir, I have a 2001 Volkswagen Passat B5 with a V-6-30 valve engine. Engine code is ATQ. I have a DTC showing P0431 "Warm up catalyst efficiency below threshold (bank 2)". I do not know exactly what this is. I know there are two sets of oxygen sensors on each bank of three cylinders.

I have two catalytic converters, and an heated oxygen sensor before each, and an oxygen sensor (non-heated type) after each catalytic converter. My car has only 33,000 miles and it is a manual transmission. I checked out the resistances of each oxygen sensor, all four of them, and they all look fine, within specs.

So I am avoiding changing the heated oxygen sensor before the catalytic converter on bank two which I thought could be causing my problem. It costs over $200.00 dollars!. I didn't think a catalytic converter could go bad. Do you have any ideas???

Please help, any suggestions or recommendations would be welcome. The car drives fine, and I don't see anything else affected.

My Volkswagen dealer wants $130.00 dollars just to tell me what the check engine light code is! But I already know what it is because I have a vag com tool. But they still insist on checking the code again and charging me for it! It's crazy!

So therefore I have avoided going to them unless I know it is the catalytic converter for sure so that it might be covered under an emissions warranty.

Thanks for any help...

A. According to this should be code # P0432. Anyhow, this could be indicative of many different things including the catalyst having a malfunction. Since you don't indicate that there are any other faults, problems in operation, or codes I would actually suspect the catalytic converter and have the dealership honor my emissions warranty and get them to repair the problem.

The car is under warranty, there should be no charge for a diagnostic if the Check Engine Light is on. The CEL comes on when emission related system malfunctions. If they insist on charging you for it, contact Volkswagen at 1-800-822-8987 and file a complaint.