What does code P2538 mean?

Q: What does code P2538 mean?

Ignition Switch Accessory Position Circuit High. P2538 indicates that the powertrain control module (PCM) has detected an abnormally high voltage on the ignition switch accessory position circuit, which is the circuit that should be powered only when the key is turned to the accessory (ACC) position. The PCM expects a specific voltage range on this input, and a reading above the normal threshold triggers the code because it suggests a short to power, an open ground, or a faulty switch.

DTC codes / P25xx · Vehicle speed, idle control and auxiliary inputs / P2538

P2538Ignition Switch Accessory Position Circuit High

P2538 indicates that the powertrain control module (PCM) has detected an abnormally high voltage on the ignition switch accessory position circuit, which is the circuit that should be powered only when the key is turned to the accessory (ACC) position. The PCM expects a specific voltage range on this input, and a reading above the normal threshold triggers the code because it suggests a short to power, an open ground, or a faulty switch.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaVehicle speed, idle control and auxiliary inputs

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.