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DTC codes / P24xx · Auxiliary emission controls / P2440
P2440 indicates that the secondary air injection (AIR) system's switching valve on bank 1 is stuck open, as detected by the engine control module (ECM) through unexpected oxygen sensor readings or valve position feedback. The ECM commands the valve to close, but the resulting air-fuel ratio or sensor response shows that air is still flowing when it should not be.
Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.
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