P0420

DTC P0420 CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD (BANK 1)

1. OUTLINE OF DIAGNOSIS
Detect the deterioration of the catalyst function.
Though the front oxygen sensor output would change slowly with a new catalyst, the sensor output with a deteriorated catalyst becomes high and the inversion time is shortened.
For this reason, the catalyst diagnosis is carried out by monitoring the front oxygen sensor output and comparing it with the front oxygen (A/F) sensor output.

2. COMPONENT DESCRIPTION






3. ENABLE CONDITION






4. GENERAL DRIVING CYCLE
Perform the diagnosis only once at a constant 60 km/h (37.3 MPH) or higher.

5. DIAGNOSTIC METHOD
After establishing the execution conditions, calculate the front oxygen (A/F) sensor lambda deviation cumulative value (Sigma |(sglmd (n) - sglmd (n_1))|) and rear oxygen sensor output voltage deviation cumulative value (Sigma |(ro2sad (n) - ro2sad (n_1))|) per 32 milliseconds x 4, and when the front oxygen (A/F) sensor lambda deviation cumulative value (Sigma |(sglmd (n) - sglmd (n_1))|) becomes the predetermined value or more, calculate the diagnostic value.

Abnormality Judgement
If the duration of time while the following conditions are met is within the time indicated, judge as NG.






Time Needed for Diagnosis: 30 - 55 seconds

Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.

Normality Judgement
Judge as OK and clear the NG if the continuous time while the following conditions are established is within the predetermined time.






Time Needed for Diagnosis: 30 - 55 seconds