P0159

DTC P0159 O2 SENSOR CIRCUIT SLOW RESPONSE (BANK 2 SENSOR 2)

1. OUTLINE OF DIAGNOSIS
Detect the slow response of rear oxygen sensor.
Judge NG when the Rich not equal to Lean response diagnosis or Lean not equal to Rich response diagnosis is NG and judge OK when both response diagnoses are OK.

[Rich -> Lean diagnosis response]
1. When the measured response time is larger than a threshold, since the A/F ratio is rich, the response time of the output change of O2 sensor when changing from Rich to Lean is measured, and it judges with NG, and when small, it judges with OK.
2. When O2 sensor voltage at the time of a fuel shut-off in deceleration return is large (rich), it judges with NG.

[Lean -> Rich diagnosis response]
1. The response time of output change of O2 sensor when an A/F ratio changes from Lean to Rich is measured, and it is referred to as NG when the measured response time is larger than a threshold.
2. It is referred to as NG when O2 sensor voltage after recovery of fuel shut-off in deceleration is small and still small.

- Diagnostic Method
Measure the response time of the output change of the oxygen sensor when the A/F ratio changes from rich to lean. And Judge NG when the measured response time is larger than the threshold value.




2. COMPONENT DESCRIPTION




3. ENABLE CONDITION
- Rich -> Lean response diagnosis

4. GENERAL DRIVING CYCLE
Perform the diagnosis only once when fuel shut-off in deceleration after rapid acceleration. (Pay attention to oxygen sensor voltage for the timing of deceleration.)




5. DIAGNOSTIC METHOD
When the oxygen sensor output voltage changes from 0.55 V (rich) to 0.25 V (lean), calculate the Min. value of response time regarded as judgment value while the output varies from 0.5 V to 0.3 V.




- Abnormality Judgment
1. Judge NG when the judgment value is larger than the threshold value after fuel shut-off in deceleration. Response time (Diagnosis value) > Threshold value -> Abnormal

NOTE:
- Variation time of rear oxygen sensor output voltage is short during fuel shut-off in deceleration. Carry out the NG judgment only after the fuel shut-off in deceleration. As for OK judgment, without the condition of fuel shut-off in deceleration, judge OK if the value is below the threshold value.
- Judge NG when the malfunction criteria are completed in 2 seconds after the recovery of fuel shut-off in deceleration which requires 6 seconds or more.

2. Judge NG when the O2 sensor voltage after recovery of fuel shut-off in deceleration is large. Judge NG when fuel shut-off in deceleration is also long (6 s or more), and although carried out the fuel shut-off in deceleration cut return, when O2 sensor voltage is large (more than 0.55 V).




- Normality Judgement
1. Judge Normal when the response time (diagnostic value) is smaller than threshold (judgment value) when changing to lean since O2 sensor voltage.
2. A normal judging is not carried out.

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

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

8. FAIL SAFE
Sub feedback control: Not allowed

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)




10. ENABLE CONDITION
- Lean -> Rich response diagnosis

11. GENERAL DRIVING CYCLE
Perform the diagnosis only once when fuel shut-off in deceleration after rapid acceleration. (Pay attention to oxygen sensor voltage for the timing of deceleration.)




12. DIAGNOSTIC METHOD
When the oxygen sensor output voltage changes from 0.25 V (lean) to 0.55 V (rich), calculate the Min. value of response time regarded as judgment value while the output varies from 0.3 V to 0.5 V.




- Abnormality Judgment
1. Judge NG when the judgment value is larger than the threshold value after recovery of fuel shut-off in deceleration.
Response time (Diagnosis value) > Threshold value -> Abnormal
2. Judge NG when the O2 sensor voltage after recovery of fuel shut-off in deceleration is small.




- Normality Judgement
1. Judge Normal when the response time (diagnostic value) is smaller than threshold (judgment value) when changing to lean since O2 sensor voltage.
Response Time (diagnosis value) less than or equal to Threshold value -> Normal
2. A normal judging is not carried out.

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

14. MALFUNCTION INDICATOR LIGHT CLEAR CONDITION
- When the OK driving cycle was completed 3 times in a row
- When "Clear Memory" was performed

15. FAIL SAFE
Sub feedback control: Not allowed

16. 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)