P0139, P0159 HO2S2
VR38
P0139 P0159
Description
The heated oxygen sensor 2, after three way catalyst 1, monitors the oxygen level in the exhaust gas on each bank.
Even if switching characteristics of the air fuel ratio (A/F) sensor 1 are shifted, the air-fuel ratio is controlled to stoichiometric, by the signal from the heated oxygen sensor 2.
This sensor is made of ceramic zirconia. The zirconia generates voltage from approximately 1 V in richer conditions to 0 V in leaner conditions.
Under normal conditions the heated oxygen sensor 2 is not used for engine control operation.
DTC Logic
DTC DETECTION LOGICThe 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 various driving conditions such as fuelcut.
| 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. |
|
| P0159 | Heated oxygen sensor 2 (bank 2) circuit slow response |
DTC CONFIRMATION PROCEDURE
1.INSPECTION START