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DTC codes / P22xx · Fuel and air metering (injector circuits) / P22F9
P22F9 means the engine computer has determined that the upstream nitrogen oxide (NOx) sensor on bank 1 is responding too slowly when the exhaust NOx concentration rises from a low level to a high level. The sensor is still producing a signal, but its signal does not change quickly enough to satisfy the monitor's expected response time, so the computer flags a performance fault rather than a complete circuit failure.
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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