What Does P0420 Mean on a 2022 Nissan Maxima?
The P0420 code on your 2022 Nissan Maxima indicates the ECM has detected that the Bank 1 catalytic converter is operating below its expected efficiency level. The 2022 Maxima features the 3.5L V6 VQ35DE engine producing 300 hp, paired with the Xtronic CVT on the D-platform. Bank 1 is the rear bank on the transversely mounted engine. The Maxima uses close-coupled converters near each exhaust manifold for rapid light-off.
With the 2022 model still relatively new, the federal emissions warranty should cover this repair if the converter or sensor is at fault.
Symptoms You Might Notice
- Check engine light illuminated
- Mild fuel economy decrease
- Faint sulfur smell
- Possible minor power loss
- Emissions test failure
Common Causes on the 2022 Maxima
1. Catalytic Converter Degradation
While the 2022 model is newer, the Maxima's 300-hp V6 generates significant exhaust heat. Drivers who enjoy the sedan's sport capabilities push exhaust temperatures higher. The close-coupled converter design means the converter receives very hot exhaust gases directly from the manifold, which can accelerate wear.
2. Downstream O2 Sensor Issue
A defective or sluggish post-cat sensor is a likely culprit on a newer Maxima. The sensor could have an internal defect or contamination from oil vapor or fuel additives. Testing the sensor response rate is the first diagnostic step.
3. Exhaust Leak
A leak at the manifold-to-converter connection or at any exhaust joint between the engine and the downstream sensor can cause false P0420 readings. On the 2022 Maxima, check for exhaust gasket integrity and loose clamps.
4. Software Calibration
Nissan may have released an ECM calibration update that adjusts P0420 detection thresholds for the 2022 Maxima. A simple reflash at the dealer could resolve the code without any parts replacement.
How to Diagnose the Problem
- Visit your Nissan dealer — The 2022 Maxima should be under emissions warranty. Let the dealer diagnose with CONSULT.
- Check for TSBs — The dealer will search for applicable technical service bulletins.
- O2 sensor data analysis — Comparing upstream and downstream sensor data identifies the root cause.
- Exhaust inspection — All connections checked for leaks.
- Software check — ECM verified for latest calibration.
Repair Options
Professional Repair (Recommended)
Your 2022 Maxima is covered by the federal emissions warranty for the catalytic converter (8 years/80,000 miles). Take it to a Nissan dealer for covered diagnosis and repair. The rear bank converter access challenge makes professional service the better choice.
DIY Repair
O2 sensor replacement is possible for experienced DIYers. Converter work on the Maxima's transverse V6 is difficult due to tight clearances and should be left to professionals, especially while under warranty.
Estimated Repair Costs
- Catalytic converter replacement: $700 - $1,600 (likely warranty-covered)
- Downstream O2 sensor: $125 - $300
- ECM software update: $0 - $150
- Exhaust leak repair: $100 - $400
Prevention Tips
- Use premium fuel as recommended for the VQ35DE
- Follow the dealer maintenance schedule
- Address any engine performance issues promptly
- Avoid prolonged aggressive driving that overheats the converter
- Keep service records for warranty documentation