DTC codes / P25xx · Vehicle speed, idle control and auxiliary inputs / P259A
P259A indicates that the powertrain control module has detected a performance fault with the turbocharger boost control position sensor B circuit, specifically that the signal is stuck low. The computer expects the sensor voltage to vary as the turbocharger vane or wastegate actuator moves, but the reading remains below the expected threshold for the current operating conditions.
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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