Your 2022 Compass shows P0420 along with hesitation during driving. While P0420 points to the catalytic converter, the accompanying hesitation suggests an underlying issue that may have caused catalyst damage—or is causing both symptoms.
Understanding P0420
The P0420 code means "Catalyst System Efficiency Below Threshold (Bank 1)." The engine computer compares front and rear oxygen sensor readings. When they're too similar, the catalyst isn't processing exhaust gases properly.
Hesitation Plus P0420
When hesitation accompanies P0420, consider:
- Misfires damaged the catalyst
- Running rich/lean stressed the catalyst
- A restricted catalyst is causing hesitation
- Separate issues creating both symptoms
Common Causes
- Catalyst degradation - Normal wear over time
- Contaminated catalyst - Oil or coolant damage
- Faulty rear O2 sensor - False efficiency reading
- Exhaust leak - Skewing sensor readings
- Previous misfire damage - Unburned fuel killed catalyst
Don't Just Replace the Cat
If something killed your catalytic converter, replacing it without fixing the root cause damages the new one. Check for:
- Oil consumption issues
- Chronic rich/lean conditions
- Recurring misfires
- Coolant leaks into combustion
Diagnostic Steps
- Check for additional codes (misfires, fuel trim)
- Compare front/rear O2 sensor readings
- Check for exhaust leaks
- Temperature test catalyst
- Verify no oil/coolant consumption
Repair Costs
- Rear O2 sensor: $150-$300
- Exhaust repair: $100-$400
- Catalytic converter: $800-$2,000
Federal emissions warranty covers the catalyst for 8 years/80,000 miles.