P1420
NOx Adsorptive Catalyst System Efficiency Below Threshold
Severity
🔴 HighCan you drive?
Do not drive — repair immediately
Approx. repair cost
$167–556 (est.)
Symptoms
- Check Engine light comes on
- Reduced engine power
- Increased fuel consumption
- Unusual odors from the exhaust system
- Dips during acceleration
Causes
- Worn or damaged NOx catalytic converter
- NOx sensor malfunction
- Problems with the catalyst regeneration system
- Contamination of the catalyst with sulfur or other substances
- Malfunction of the urea injection system (AdBlue) in diesel engines
How to Fix
- Diagnostics of the condition of the catalytic converter
- Checking NOx sensors and their wiring
- Checking the catalyst regeneration system
- Cleaning or replacing the NOx catalyst
- Checking and servicing the AdBlue injection system (if equipped)