david@aladcoservices.com

I am getting codes #491 and #492 "Secondary Air" Bank 1 & 2. Does anyone know what could be causing this?

Hambone101

I had P0491, as it turned out it was the combination valve. My mech and I checked both just to be sure, and found that both could not hold vacuum. Start there, hope that helps.

bm196, '02 4.2

A few weeks ago my PO 490, 491 codes turned out to be two leaking vacuum lines at top rear of engine. Indy fix for $154.00.

makav3li

Thats calling out ur secondary air injection system, both banks dont seem to be getting enough air flow. The air injection pump is only activated once u start up and only when the coolant temp is low, it sends air into the cats for faster and cold startups. I'd find the air injection pump, turn on your car then check to see if u can tell if the pump is working or not...if not, i'd check the fuse, mine was under my hood and next the the battery area. I have the same codes and i think my pump is bad

david@aladcoservices.com

Thanks