P0420 on Nissan: Catalyst System Efficiency Below Threshold (Bank 1)
Severity: 2 of 4
Usually safe to drive for a short time if the light is steady and the car runs normally. Fix the cause before it gets worse, because a converter that is overheating from misfires can become a fire risk and will fail completely. If the light flashes, or you smell strong sulfur or see a glowing red converter, park it.
Estimate range covers the repairs listed below; see the cost breakdown. A flashing check engine light, a hot temperature gauge, or brakes that feel different mean stop driving and get help.
What P0420 usually means on a Nissan
P0420 is well known on Nissan vehicles. Nissan campaigns have replaced the exhaust manifold and catalyst on certain 2018 Altima and Rogue models and extended catalyst coverage on certain 2010 to 2012 Altima SULEV models, so checking NHTSA with your VIN is especially important.
Most likely causes on Nissan vehicles
- Recall or warranty coverage
- Exhaust leak
- Rear oxygen sensor
- Worn converter
Order reflects cost and likelihood in general; your vehicle may differ. Confirm with testing before buying parts.
Nissan specific tips
- Search recalls before paying for parts.
- Some Nissan engines integrate the converter into the exhaust manifold, which increases labor.
Estimated repair cost
This is an estimate, built from typical parts price ranges plus labor hours times an assumed shop rate of $110 to $190 per hour. Actual prices vary by vehicle, region, and shop. Diagnosis fees are often extra.
| Repair | Parts | Labor | Estimate (low / high) |
|---|---|---|---|
| Rear oxygen sensor | $30 to $120 | 0.3 to 1.0 h | $30 + 0.3 × $110 = $63 $120 + 1.0 × $190 = $310 |
| Exhaust gasket or flex pipe repair | $15 to $150 | 0.5 to 1.5 h | $15 + 0.5 × $110 = $70 $150 + 1.5 × $190 = $435 |
| Catalytic converter (aftermarket, direct fit) | $250 to $1,400 | 1.0 to 2.5 h | $250 + 1.0 × $110 = $360 $1,400 + 2.5 × $190 = $1,875 |
Costs are generic for this code; parts and labor on some Nissan models may run higher.
Watch a repair video
P0420 How To Diagnose A Bad Catalytic Converter (EricTheCarGuy). Third-party video, loads from YouTube (privacy-enhanced mode) only when you press play. Procedures vary by vehicle. Search YouTube for “P0420 Nissan fix” videos.
Repair manuals
Step-by-step service manuals for Nissan with torque specs and wiring diagrams:
Haynes manuals for Nissan Chilton manuals
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Check Nissan recalls
Enter your VIN at the NHTSA recall lookup before paying for repairs.
FAQ
Why is P0420 so common on Nissans?
Close coupled converters run very hot and some engines consume oil, both of which age the catalyst.
Read the full P0420 guide or more Nissan check engine notes.