DTC P0133 Or DTC P0134: Notes

Code Definition

DTC P0133: Front Heated Oxygen Sensor (HO2S) Circuit Slow Response
DTC P0134: Front Heated Oxygen Sensor (HO2S) Circuit Inactive

NOTE: There is a front HO2S (Bank 1, Sensor 1) before and a rear HO2S (Bank 1, Sensor 2) after the catalytic converter. The front HO2S measures oxygen content of exhaust gases and is used to control air/fuel mixture. The rear HO2S is used to determine the efficiency of the catalytic converter. ECM calculates catalytic converter efficiency by comparing front and rear HO2S signals.