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.
MALFUNCTION A
To judge the malfunctions of heated oxygen sensor 2, ECM monitors whether the voltage is unusually high during various driving conditions such as fuelcut.

PBIB1848E.JPG

MALFUNCTION B
To judge the malfunctions of heated oxygen sensor 2, ECM monitors whether the minimum voltage of sensor is sufficiently low during various driving conditions such as fuelcut.

PBIB2376E.JPG

DTC No.
Trouble diagnosis name
DTC detecting condition
Possible cause
P0138
Heated oxygen sensor 2 (bank 1) 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 does not reach to the specified voltage.
  • Harness or connectors
    (The sensor circuit is open or shorted)
  • Heated oxygen sensor 2
  • Fuel pressure
  • Fuel injector
P0158
Heated oxygen sensor 2 (bank 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 does not reach to the specified voltage.
  • Harness or connectors
    (The sensor circuit is open or shorted)
  • Heated oxygen sensor 2
  • Fuel pressure
  • Fuel injector

 
 DTC CONFIRMATION PROCEDURE

 
 1.PRECONDITIONING
 
 2.PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION A
 
 3.PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION B
 
 4.PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION B AGAIN
 
 5.PERFORM COMPONENT FUNCTION CHECK FOR MALFUNCTION B