DTC codes / P26xx · Computer and output circuits / P26AB
P26AB means the engine computer has commanded the coolant bypass valve to move, but the valve's position feedback or the resulting temperature change indicates it is stuck or stuck open. The powertrain control module (PCM) monitors the valve's response and sets this code when the actual state does not match the commanded state within a calibrated time.
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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