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DTC codes / P25xx · Vehicle speed, idle control and auxiliary inputs / P25FB
P25FB is a generic powertrain code indicating that the engine control module (ECM) has detected an out-of-range condition in the control circuit for the 'C' turbocharger or supercharger bypass valve. The ECM monitors the electrical circuit that commands the valve to open or close, and it sets this code when the circuit's performance does not match expected values, such as an open, short, or excessive current draw. This fault can affect boost control and may lead to reduced engine performance or a forced limp mode.
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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