Smog & Air Pumps

Buying guide: Smog & Air Pumps

There are 36 listings covering 1998 through 2018 with a median price around $216. The secondary air injection pump pushes fresh air into the exhaust stream for the first minute or two after a cold start, so the converter lights off sooner and hydrocarbon emissions drop during warm-up. It runs briefly and then shuts off, which is why a failing pump often sets a code without any symptom the driver notices.

Dorman supplies the largest share with 15 listings, with ACDelco close behind at 14 and VEMO and Motorcraft covering the rest. Chevrolet, Buick, Cadillac, Audi and BMW make up most of the applications.

Electric pumps, which are the majority of what is listed here, are controlled by the ECU and monitored for current draw. Combi-valves and check valves sit downstream and fail separately. Earlier mechanical pumps are belt-driven and are a different repair entirely. Match the type before ordering.

The codes tell you which part to look at. P0410 and P0411 point at the pump and the airflow it produces. P2435 and related codes point at the combi-valve or the pressure sensor. Replacing the pump for a valve fault is the most common wasted repair in this system, so worth reading which code is actually stored before buying anything.

Confirm the pump runs at all before replacing it. A pump that is silent on a cold start has either failed or lost its relay, and the relay costs a fraction of the pump. If the pump runs and the code persists, the fault is usually downstream at the valve or in the air passages in the cylinder head, which carbon up on older engines.