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DTC codes / P22xx · Fuel and air metering (injector circuits) / P22AA
P22AA indicates that the powertrain control module (PCM) has detected an intermittent fault in the heater sense circuit for the downstream nitrogen oxide (NOx) sensor on bank 1. The PCM monitors the heater element's electrical current or voltage and flags this code when the signal momentarily drops out or becomes erratic, rather than failing completely.
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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