DTC P0138: Rear Ho2S Circuit, High Input: Condition

DTC is set when rear HO2S voltage is more than .45 volt for 6 seconds when vehicle is decelerating (fuel cut). This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are:

• Rear HO2S malfunction.
• Short circuit between rear HO2S and PCM.