Subaru P0420 Error Code: How to Fix It

Q: Can I drive my Subaru with P0420 error code?

Yes, you can drive short distances, but the vehicle will fail emissions testing and fuel economy may decrease. Address the issue promptly to prevent potential damage to other exhaust components.

Q: How much does it cost to fix Subaru P0420?

Costs range from $20 for catalytic converter cleaner to $800-1500 for catalytic converter replacement. Oxygen sensor replacement typically costs $150-400 depending on which sensors need replacement.

Q: Why is P0420 common on Subaru vehicles?

Subaru's horizontally opposed Boxer engines run hotter than traditional engines, which can cause catalytic converters to degrade faster. Additionally, the flat engine design can lead to oil consumption issues that contaminate the catalyst.

Q: Will catalytic converter cleaner fix P0420?

Catalytic converter cleaner can sometimes resolve P0420 if the issue is carbon buildup, but it won't fix a physically damaged or worn-out converter. It's worth trying as a first step since it's inexpensive.

Q: How long do Subaru catalytic converters last?

Subaru catalytic converters typically last 80,000-120,000 miles, though this can vary based on driving conditions, maintenance, and whether the engine has oil consumption issues common in some Subaru models.

Abstract

The Subaru P0420 error code indicates your catalytic converter isn't working efficiently enough to meet emissions standards. This common issue on Subaru's Boxer engines typically means the catalyst system on Bank 1 has fallen below the required threshold for converting harmful exhaust gases.