FixVault

DTC Detection Logic

The heated oxygen sensor 3 has a much longer switching time between rich and lean than the air fuel ratio (A/F) sensor 1. The oxygen storage capacity of the three way catalyst (manifold) causes the longer switching time. To judge the malfunctions of heated oxygen sensor 3, ECM monitors whether the minimum voltage of sensor is sufficiently low during the various driving condition such as fuel cut.

Fig 1: Voltage Graph
G05694993Courtesy of NISSAN MOTOR CO., U.S.A.
DTC DETECTING CONDITION AND POSSIBLE CAUSE

DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0143 Heated oxygen sensor 3 circuit high voltage 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 3
  • Fuel pressure
  • Fuel injector