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Home >> Nissan-Datsun >> 2008 >> Sentra SL >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 8 (Engine Control System - DTCS P0137 To P0445 (Qr25DE)) >> DTC P0137, P0157 Ho2S2 >> On Board Diagnosis Logic

On Board Diagnosis Logic

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The heated oxygen sensor 2 has a much longer switching time between rich and lean than the air fuel ratio (A/F) sensor 1. The oxygen storage capacity before the three way catalyst (manifold) causes the longer switching time. To judge the malfunctions of heated oxygen sensor 2, ECM monitors whether the maximum voltage of the sensor is sufficiently high during the various driving condition such as fuel-cut.

Fig 1: Heated Oxygen Sensor 2 Waveform
G04875059Courtesy of NISSAN MOTOR CO., U.S.A.
DTC DETECTING CONDITION AND POSSIBLE CAUSES CHART

DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0137
0137
(Bank 1)
Heated oxygen sensor 2 circuit low voltage The maximum voltage from the sensor is not reached to the specified voltage.
  • Harness or connectors (Heated oxygen sensor 2 circuit open or shorted.)
  • Heated oxygen sensor 2
  • Fuel pressure
  • Fuel injector
  • Intake air leaks
P0157
0157
(Bank 2)