Diagnostic Method
When the oxygen sensor output voltage changes from 0.55 V (rich) to 0.25 V (lean), calculate the minimum response time for output change between 0.5V and 0.3V 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. Carry out the NG judgment only after the fuel shut-off in deceleration. 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. | > 327 milliseconds |
| Time at over 550 mV | > 2 sec. |
Time Needed for Diagnosis: 1 time
Malfunction Indicator Light Illumination: Illuminates when malfunction occurs 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. | ≤ 327 milliseconds |
Calculate the minimum value of 0.3 V to 0.5 V output change response time as judgment value, when the 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 voltage drops from 500 mV to 250 mV. | > 2 sec. |
| Time at less than 250 mv | > 120 sec. |
Time Needed for Diagnosis: 1 time
Malfunction Indicator Light Illumination: Illuminates when malfunction occurs 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. |