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 (manifold) 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 fuel cut.
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 fuel-cut.
| 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. |
|
| B) | The minimum voltage from the sensor is not reached to the specified voltage. |
|
||
| P0158 | Heated oxygen sensor 2 (bank 2) circuit high voltage | A) | An excessively high voltage from the sensor is sent to ECM. |
|
| B) | The minimum voltage from the sensor is not reached to the specified voltage. |
|
||
- PRECONDITIONING
If DTC Confirmation Procedure has been previously conducted, always perform the following before conducting the next test.
- Turn ignition switch OFF and wait at least 10 seconds.
- Turn ignition switch ON.
- Turn ignition switch OFF and wait at least 10 seconds.
: GO TO 2.
- PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION A
- Start engine and warm it up to the normal operating temperature.
- Turn ignition switch OFF and wait at least 10 seconds.
- Turn ignition switch ON.
- Turn ignition switch OFF and wait at least 10 seconds.
- Start engine and keep the engine speed between 3, 500 and 4, 000 rpm for at least 1 minute under no load.
- Let engine idle for 2 minutes.
- Check 1st trip DTC.
Is 1st trip DTC detected?
YES: Go to "DIAGNOSIS PROCEDURE ".
NO-1: With CONSULT: GO TO 3.
NO-2: Without CONSULT: GO TO 5.
- PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION B NOTE: For better results, perform "DTC WORK SUPPORT" at a temperature of 0 to 30°C (32 to 86°F).
- Select "DATA MONITOR" mode with CONSULT.
- Start engine and warm it up to the normal operating temperature.
- Turn ignition switch OFF and wait at least 10 seconds.
- Turn ignition switch ON.
- Turn ignition switch OFF and wait at least 10 seconds.
- Start engine and keep the engine speed between 3, 500 and 4, 000 rpm for at least 1 minute under no load.
- Let engine idle for 1 minute.
- Check that "COOLAN TEMP/S" indicates more than 70°C (158°F).
If not, warm up engine and go to next step when "COOLAN TEMP/S" indication reaches 70°C (158°F).
- Open engine hood.
- Select "HO2S2 (B1) P1146" (for DTC P0138) or "HO2S2 (B2) P1166" (for DTC P0158) of "HO2S2" in "DTC WORK SUPPORT" mode with CONSULT.
- Follow the instruction of CONSULT display.NOTE: It will take at most 10 minutes until "COMPLETED" is displayed.
- Touch "SELF-DIAG RESULTS".
Which is displayed on CONSULT screen?
OK: INSPECTION END
NG: Go to "DIAGNOSIS PROCEDURE ".
CON NOT BE DIAGNOSED: GO TO 4.
- PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION B AGAIN
- Turn ignition switch OFF and leave the vehicle in a cool place (soak the vehicle).
- Perform DTC confirmation procedure again.
: GO TO 3.
- PERFORM COMPONENT FUNCTION CHECK FOR MALFUNCTION B
Perform component function check. Refer to "COMPONENT FUNCTION CHECK ".
NOTE: Use component function check to check the overall function of the heated oxygen sensor 2 circuit. During this check, a 1st trip DTC might not be confirmed.Is the inspection result normal?
YES: INSPECTION END
NO: Go to "DIAGNOSIS PROCEDURE ".