Component Inspection

P0420 Catalyst System Efficiency below Threshold (Bank 1)

Inspection/Repair - Component Inspection

Component Inspection

1. Rear HO2S (B1S2) check
(1) B1S2 visual check
- Check assembling state of B1S2. (Check the interference between sensor wiring and exhaust pipe.)
- Check corrosion, contamination, or damage on sensor terminal and connector.
(2) Is there something wrong?
YES
1) Repair as necessary and then, go to "Verification of Vehicle Repair" procedure.
NO
1) Go to "Catalyst converter check" procedure.
2. Catalyst converter check
(1) Catalyst converter visual check
- Check discoloration by over-heating.
- Check deflection or crack (hole).
- Check noise.
(2) Check whether the catalyst converter is genuine.
(3) Is there something wrong?
YES
1) Substitute with a known-good Catalyst Converter and check for proper operation. If the problem is corrected, replace Catalyst Converter and then go to "Verification of Vehicle Repair" procedure.
NO
1) Substitute with a known-good ECM and check for proper operation. If the problem is corrected,replace ECM and then go to "Verification of Vehicle Repair" procedure.

CAUTION:
There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by PCM.
Before or after testing PCM on the vehicle, use this function to reuse the PCM on the others