Engine Error
P0420
Catalyst System Efficiency Below Threshold (Bank 1)
Severity
Medium
Symptoms
Check engine light, reduced fuel economy, sulfur smell from exhaust
Common Causes
- Faulty catalytic converter
- Exhaust leaks
- Oxygen sensor failure
- Engine misfires
How to Fix
- 1 Inspect exhaust for leaks
- 2 Test oxygen sensor signals
- 3 Replace catalytic converter
- 4 Fix engine misfire issues
Estimated Repair Cost
USD
$400
–
$2500
Catalytic converter unit: $400 - $2,500