System Inspection

P0420 Catalyst System Efficiency below Threshold (Bank 1)

Inspection/Repair - System Inspection

Exhaust system Inspection

1. Visually/physically inspect the following conditions:
'- Exhaust system between HO2S and Three way catalyst for air leakage, restriction and damage.
'- Damage, and for loose or missing hardware:
2. Was a problem found in any of the above areas?






Rear HO2S Inspection

1. Visually/physically inspect the rear HO2S for the following conditions:
'- Ensure that the HO2S is securely installed. (Pigtail and wiring harness not making contact with the exhaust pipe)
'- Check for corrosion on terminals
'- Check for terminal tension (at the HO2S and at the PCM)
'- Any road damage
2. Was a problem found in any of the above areas?






TWC Inspection

1. Visually/physically inspect the three-way catalyst (TWC) converter for the following damage:
'- Severe discoloration caused by excessive temperature
'- Dents and holes
'- Internal rattle caused by a damaged catalyst
2. Also, ensure that the TWC is a proper original equipment manufacturer part.
3. Was a problem found?