H4SO U5

DTC P0031 HO2S HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 1)

1. OUTLINE OF DIAGNOSIS
Detect front oxygen (A/F) sensor heater open or short circuit.

The front oxygen (A/F) sensor heater performs duty control, and the output terminal voltage at ON is 0 V, and the output terminal voltage at OFF is the battery voltage.

Judge as NG when the terminal voltage remains Low.


2. COMPONENT DESCRIPTION






3. ENABLE CONDITION

Enable Conditions:

4. GENERAL DRIVING CYCLE
Always perform the diagnosis continuously.

5. DIAGNOSTIC METHOD

- Abnormality Judgment
If the duration of time while the following conditions are met is longer than the time indicated, judge as NG.






Time Needed for Diagnosis: 4 ms • 250 time

Malfunction Indicator Light Illumination: Illuminates as soon as a malfunction occurs.

- Normality Judgment
Judge as OK and clear the NG if the continuous time while the following conditions are established is more than the predetermined time.







Time Needed for Diagnosis: Less than 1 second

6. DTC CLEAR CONDITION
- When the OK idling cycle is completed 40 times in a row
- When "Clear Memory" is performed

7. MALFUNCTION INDICATOR LIGHT CLEAR CONDITIONS
- When the OK driving cycle is completed 3 times in a row
- When "Clear Memory" is performed

8. FAIL SAFE
- Front oxygen (A/F) sensor heater control: Not allowed to turn on heater.
- A/F main learning: Not allowed to calculate the A/F main learning compensation factor.
- A/F sub learning: Not allowed to calculate the A/F sub learning compensation factor.
- Purge control: Not allowed to purge.

9. ECM OPERATION AT DTC SETTING
- Memorize the freeze frame data. (For test mode $02)
- Memorize the diagnostic value and trouble standard value. (For test mode $06)