Diagnostic Method
When the rear oxygen sensor output voltage changes from 0.55 V (rich) to 0.25 V (lean), calculate the minimum response time for output change between 0.5 V and 0.3 V for the judgment criteria.
Abnormality Judgment
- Judge as NG when the judgment value is larger than the threshold value after deceleration fuel cut. Response time (diagnosis value) > threshold value → abnormalNOTE: Variation time of rear oxygen sensor output voltage is short during fuel shut-off in deceleration. NG judgment should be performed with the condition of deceleration fuel cut. Even without deceleration fuel cut, judge as OK if the value is below the threshold.
When the deceleration fuel cut off time is more than 6 seconds, judge as NG if the following criteria are met 2 seconds after recovering from the deceleration fuel cut.
- Judge as NG when the oxygen sensor voltage at recovery from a deceleration fuel cut, is large. If the fuel cut time in a deceleration fuel cut is long (more than 6 s), and even after recovering from a deceleration fuel cut, the oxygen sensor voltage is high (0.55 V or more), judge as NG.
Judgment Value
| Malfunction Criteria | Threshold Value |
|---|---|
| Shortest time change from rich (500 mV O2 output) to lean (300 mV) if voltage reduces from 550 mV to 250 mV. or |
> 0.327 sec. |
| Longest time over 550 mV | > 2 sec. |
Time Needed for Diagnosis: 1 time
Malfunction Indicator Light Illumination: Illuminates when malfunctions occur in 2 continuous driving cycles.
Normality Judgment
- Regardless of a deceleration fuel cut, if the response time (diagnosis value) when the oxygen sensor voltage has changed from rich to lean is shorter than the threshold value (judgment value), judge as a normal condition.
Response time (diagnosis value) ≤ threshold value → normal
- Do not judge as a normal condition.
Judge as OK when the criteria below are met.
Judgment Value
| Malfunction Criteria | Threshold Value |
|---|---|
| Shortest time change from rich (500 mV O2 output) to lean (300 mV) if voltage reduces from 550 mV to 250 mV. | ≤ 0.327 sec. |
Calculate the minimum value of 0.3 V to 0.5 V output change response time as judgment value when the rear oxygen sensor output voltage changes from 0.25 V (lean) to 0.55 V (rich).
Abnormality Judgment
- Judge as NG when the judgment value is larger than the threshold value after deceleration fuel cut. Response time (diagnosis value) > threshold value → abnormal
- If the oxygen sensor voltage is small after recovering from a deceleration fuel cut, and remains small, judge as NG.
Judgment Value
| Malfunction Criteria | Threshold Value |
|---|---|
| Shortest time change from lean (300 mV O2 output) to rich (500 mV) when the voltage drops from 500 mV to 250 mV. or |
> 2 sec. |
| Longest time under 250 mV | > 120 sec. |
Time Needed for Diagnosis: 1 time
Malfunction Indicator Light Illumination: Illuminates when malfunctions occur in 2 continuous driving cycles.
Normality Judgment
- Regardless of a deceleration fuel cut, if the response time (diagnosis value) when the oxygen sensor voltage has changed from rich to lean is shorter than the threshold value (judgment value), judge as a normal condition.
Response time (diagnosis value) ≤ threshold value → normal
- Do not judge as a normal condition.
Judge as OK when the criteria below are met.
Judgment Value
| Malfunction Criteria | Threshold Value |
|---|---|
| Shortest time change from lean (300 mV O2 output) to rich (500 mV) when voltage drops from 550 mV to 250 mV. | ≤ 2 sec. |