Troubleshooting

DTC P0155 OXYGEN SENSOR HEATER CIRCUIT MALFUNCTION (BANK 2 SENSOR 1)

CIRCUIT DESCRIPTION

DTC Detecting Condition:

A thermistor built in the water temperature sensor changes the resistance value according to the water temperature.

The structure of the sensor and connection to the ECM is the same as the those of the air temperature sensor.

HINT: The ECM provides a pulse width modulated control circuit to adjust current through the heater. The A/F ratio sensor heater circuit uses a relay on the B+ side of the circuit.

Wiring Diagram:

Step 1 - 3:

INSPECTION PROCEDURE

HINT: Read freeze frame data using the hand-held tester or the OBD II scan tool, as freeze frame data records the engine conditions when the malfunction is detected. When troubleshooting, this is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.