Detection Condition
WARNING: This page is about a different car, the 2002 Mazda Tribute. However, it is still accessible from the selected car via links, so may be relevant.
DTC P0135 indicates HO2S-11 heater circuit (front Bank 1 on 3.0L or front on 2.0L) is open, shorted to ground, shorted to VPWR or has low or high current draw.
DTC P0141 indicates HO2S-12 heater circuit (rear) is open, shorted to ground, shorted to VPWR or has low or high current draw.
DTC P0155 indicates HO2S-21 heater circuit (front Bank 2 on 3.0L) is open, shorted to ground, shorted to VPWR or has low or high current draw.
DTC P0161 indicates HO2S-22 heater circuit (rear) is open, shorted to ground, shorted to VPWR or has low or high current draw.
HO2S heater heats HO2S sensor to temperatures of 1400°F (760°C). VPWR circuit supplies voltage to heater with PCM completing circuit ground when proper conditions are present.