DTC P0136, P1137 Or P1138: Right Rear Ho2S Circuit Malfunction: Condition
WARNING: This page is about a different car, the 2002 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.
DTC P0136 is set when Powertrain Control Module (PCM) detects input voltage from right rear heated oxygen sensor (HO2S) heater less than anticipated. DTC P1137 is set when right rear HO2S is not switching (lean condition). DTC P1138 is set when right rear HO2S is not switching (rich condition). DTC P1137 and P1138 can only be retrieved during KOER self-test when fuel control is fluctuating between rich and lean. Possible causes are:
- Open or short in circuits.
- Exhaust leaks.
- Contaminated or damaged right rear HO2S.