4 months ago (July) my check engine was caused by codes 442 and 446, the dealer said to replace the air pump, valve, and relay. Dealer turned off the light and it stayed off until last week. This time I used a generic scanner to read and clear P0410 "Secondary air injection system malfunction", the CE light again stays off. I can't find 442 or 446 in the Haynes manual and haven't figured out how to map generic diagnostic trouble codes to Volvo codes but I guess the same thing caused the CE light both times.

I am thinking I will replace just the air valve, and remove and dry out the pump without replacing it. I don't see anything to lose by starting with the valve and seeing if that fixes the problem, if it continues I will get a new pump (or clear the code every few months). Anything wrong with that approach? Anything else I should do, like clean electrical contacts on the relay or something? Another poster sent me (offline) instructions for removing/drying/replacing the pump, is there anything online about it? I can't find anything in bay 13 but I could have missed it.

Related question: Other posts indicate the new valve fixes the problem with the original. I also have a 95 850, can I look at the valve and tell whether it is the new or old one (only had the car a month)? Is it worth replacing the valve to protect the pump or do I figure if it has lasted this long it is ok?

TIA,

Terry