P0421 Warm up catalyst Efficiency Below Threshold (bank 1)
Check Conditions:
Engine speed is lower than 3,000 r/min.
The throttle valve is open.
Volume airflow sensor output frequency is between 69 and 169 Hz.
More than 3 seconds has elapsed after the above-mentioned three conditions have been met.
Intake air temperature is higher than −10°C (14°F).
Barometric pressure is higher than 76 kPa (11 psi).
Under the closed loop air/fuel ratio control.
Vehicle speed is 1.5 km/h (0.93 mph) or more.
The PCM monitors for this condition for 7 cycles of 12 seconds each during the drive cycle.
Short-term fuel trim is higher than −30 percent and lower than +25 percent.
The cumulative volume airflow sensor output frequency for every 2 seconds is higher than 4,000 Hz.
Judgment Criteria:
The right bank heated oxygen sensor (rear) signal frequency devided by right bank heated oxygen sensor (front) signal frequency = 0.75 or more.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are: )
- Right bank side catalytic converter deteriorated.
- Right bank heated oxygen sensor failed.
- PCM failed.
Check Conditions:
Engine speed is lower than 3,000 r/min.
The throttle valve is open.
Volume airflow sensor output frequency is between 69 and 169 Hz.
More than 3 seconds has elapsed after the above-mentioned three conditions have been met.
Intake air temperature is higher than −10°C (14°F).
Barometric pressure is higher than 76 kPa (11 psi).
Under the closed loop air/fuel ratio control.
Vehicle speed is 1.5 km/h (0.93 mph) or more.
The PCM monitors for this condition for 7 cycles of 12 seconds each during the drive cycle.
Short-term fuel trim is higher than −30 percent and lower than +25 percent.
The cumulative volume airflow sensor output frequency for every 2 seconds is higher than 4,000 Hz.
Judgment Criteria:
The right bank heated oxygen sensor (rear) signal frequency devided by right bank heated oxygen sensor (front) signal frequency = 0.75 or more.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are: )
- Right bank side catalytic converter deteriorated.
- Right bank heated oxygen sensor failed.
- PCM failed.