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Home >> Infiniti >> 2011 >> EX35 Base, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - DTCS P0130 Through P0445 >> DTC P0139, P0159: Ho2S2 >> DTC Logic >> DTC Detection Logic
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DTC Detection Logic

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 of the three way catalyst 1 causes the longer switching time. To judge the malfunctions of heated oxygen sensor 2, ECM monitors whether the switching response of the sensor's voltage is faster than specified during the various driving condition such as fuel-cut.

Fig 1: Heated Oxygen Sensor 2 Voltage Signal Pattern
G07165025Courtesy of NISSAN MOTOR CO., U.S.A.
DTC DETECTION LOGIC

DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0139 Heated oxygen sensor 2 (bank 1) circuit slow response It takes more time for the sensor to respond between rich and lean than the specified time.
  • Harness or connectors (The sensor circuit is open or shorted)
  • Heated oxygen sensor 2
  • Fuel pressure
  • Fuel injector
  • Intake air leaks
P0159 Heated oxygen sensor 2 (bank 2) circuit slow response