What does code P1143 mean?

Q: What does code P1143 mean?

HO2S Bank 1 Sensor 3 Lean Or Low Voltage. P1143 on a GM vehicle means the powertrain control module (PCM) has detected that the downstream heated oxygen sensor (HO2S) on bank 1, sensor 3 is reporting a lean condition or a voltage that stays lower than expected. The PCM monitors this sensor after the catalytic converter to judge catalyst efficiency and fuel control, and it sets the code when the signal remains below the calibrated lean threshold for too long.

DTC codes / GM codes / P1143

P1143 · GMHO2S Bank 1 Sensor 3 Lean Or Low Voltage

P1143 on a GM vehicle means the powertrain control module (PCM) has detected that the downstream heated oxygen sensor (HO2S) on bank 1, sensor 3 is reporting a lean condition or a voltage that stays lower than expected. The PCM monitors this sensor after the catalytic converter to judge catalyst efficiency and fuel control, and it sets the code when the signal remains below the calibrated lean threshold for too long.

SystemPowertrain

Code typeGM specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

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