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DTC codes / GM codes / P1138

P1138 · GMO2 Sensor High Voltage During Decel Fuel Cutoff

P1138 on a GM vehicle means the powertrain control module (PCM) saw the upstream oxygen (O2) sensor signal stay at a high voltage during deceleration fuel cutoff, when the sensor should read lean. The PCM commands fuel shutoff on decel, expects the O2 sensor to drop to a low voltage, and flags this code when the signal remains high instead.

SystemPowertrain
Code typeGM specific
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering
Running on fumes Free guides aren't free to make. Top up the tank. Any amount, one time. Fuel the Garage