P0420
Catalyst System Efficiency Below Threshold Bank 1
P0420 is an OBD-II diagnostic trouble code meaning: Catalyst System Efficiency Below Threshold Bank 1. Common causes: worn or damaged catalytic converter, malfunction of oxygen sensors. Estimated repair cost: $167–556.
Symptoms
- Check Engine light comes on
- Reduced engine power
- Increased fuel consumption
- Unusual smell from the exhaust pipe
Causes
- Worn or damaged catalytic converter
- Malfunction of oxygen sensors
- Leaks in the exhaust system
- Misfires leading to converter overheating
- Use of low-quality fuel
How to Fix
- Check the condition of the oxygen sensors
- Inspect the exhaust system for leaks
- Check the catalytic converter for blockage or damage.
- If necessary, replace the neutralizer or oxygen sensors
Related codes
Error P0420 by Vehicle Brand
FAQ
What does the P0420 code mean?
P0420 is an OBD-II diagnostic trouble code that indicates: Catalyst System Efficiency Below Threshold Bank 1
What causes a P0420 error code?
The most common causes of P0420 include: Worn or damaged catalytic converter; Malfunction of oxygen sensors; Leaks in the exhaust system; Misfires leading to converter overheating.
How do I fix a P0420 diagnostic trouble code?
To fix P0420: Check the condition of the oxygen sensors. Inspect the exhaust system for leaks. Check the catalytic converter for blockage or damage.. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with P0420?
Limited driving only, diagnose soon
How much does it cost to fix P0420?
The estimated repair cost for P0420 is $167–556. Actual cost depends on your vehicle, location, and labor rates.
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