16804 error code. Catalyst System: Bank 1: Efficiency below threshold.


My newly acquired A2 which had done just 34000 miles and barely any miles in the last 10 years has just had the engine light pop up.

This is the code which it says. 16804.

The previous owner had just had the car MOTed in July. Is this a serious issue or an easy fix?

Thanks for your input.


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Both my FSI and 1.4 petrol do this intermittently. With the 1.4, the ,ight will normally go off after a while. I have to reset the FSi. Ut both score really well on emissions for the MOT so it's never caused me a problem. It may he the cat degrading over time.


@Teresa thanks so much for your reply. I will reset the light and see if it comes back on. As long as it is safe to drive at this point I’m happy. 😃