FixVault

Malfunction B

To judge the malfunctions of heated oxygen sensor 2, ECM monitors whether the minimum voltage of sensor is sufficiently low during the various driving condition such as fuel-cut.

Fig 1: Voltage Graph
G05694987Courtesy of NISSAN MOTOR CO., U.S.A.
DTC DETECTING CONDITION AND POSSIBLE CAUSE

DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0138 Heated oxygen sensor 2 circuit high voltage A) An excessively high voltage from the sensor is sent to ECM.
  • Harness or connectors

    (The sensor circuit is open or shorted)

  • Heated oxygen sensor 2
B) The minimum voltage from the sensor is not reached to the specified voltage.
  • Harness or connectors

    (The sensor circuit is open or shorted)

  • Heated oxygen sensor 2
  • Fuel pressure
  • Fuel injector