P2259AIR System Control B Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2259 is the low-level fault of the second secondary air control circuit, B. A second circuit exists where an engine uses two AIR pumps, two relays or a separately switched air valve; circuit A keeps its own codes P2257/P2258. A low reading usually means the control wire has contact with ground. If the relay is switched to ground by the ECM, such a short can energise it permanently, so the pump or valve keeps running after the warm-up phase and may overheat. No manufacturer publishes a threshold for circuit B; GM merely names P2259 in the keyword list of its connector-check bulletin PIP5094 for 2014 and older models. For circuit A, GM's 2018 tables judge the low-side driver over 20 of 25 samples as a Type B fault. CARB requires that secondary air systems be monitored. The engine itself runs normally.
- What you may notice
- MIL on
- Secondary air pump audible for longer than usual or while warm
- Blown fuse of the secondary air pump after a long run
- Likely causes
- LikelyControl wire of circuit B chafed against the body or engine and shorted to ground
- PossibleRelay or air valve B with a shorted winding
- RareCorroded connector at relay B or the air valve
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.