What Does P0420 Mean on a 2023 Nissan Murano?
The P0420 code on your 2023 Nissan Murano indicates the Bank 1 catalytic converter is operating below its efficiency threshold. The 2023 Murano is the final model year for this generation, powered by the 3.5L V6 VQ35DE engine producing 260 hp with the Xtronic CVT on the D-platform. Bank 1 is the rear cylinder bank on the transversely mounted engine. The close-coupled converter design positions the converter directly against the exhaust manifold.
As a relatively new vehicle, the 2023 Murano should be under multiple warranty coverages. A dealer visit is the recommended course of action.
Symptoms You Might Notice
- Steady check engine light
- Slight fuel economy decrease
- Faint sulfur smell from exhaust
- Minor hesitation on acceleration
- Emissions test failure
Common Causes on the 2023 Murano
1. Premature Converter Failure
Even on a newer Murano, the VQ35DE's converter can fail prematurely if there is a manufacturing defect. The close-coupled design subjects the converter to extreme temperatures immediately at startup, which stresses the substrate. A defective catalyst coating or cracked substrate can cause underperformance.
2. O2 Sensor Malfunction
A defective or degraded downstream oxygen sensor is the most likely cause on a low-mileage 2023 model. Sensor contamination from oil vapor, fuel additives, or a factory defect can produce false P0420 readings.
3. Software Issue
As the final year of this Murano generation, the 2023 model benefits from years of software refinement. However, calibration updates are still possible. A dealer reflash may resolve the code.
4. Exhaust Leak
A gasket or connection issue in the exhaust system can allow air intrusion that affects downstream O2 sensor readings. Check the manifold-to-converter joint and the flex pipe section.
How to Diagnose the Problem
- Dealer diagnosis — Your 2023 Murano is under warranty. Let the dealer diagnose with CONSULT tools.
- TSB check — The dealer will search for any applicable service bulletins.
- O2 sensor data review — Live data comparison identifies sensor vs converter issues.
- Exhaust inspection — All connections and gaskets checked for leaks.
- Converter efficiency test — Temperature testing confirms converter health.
Repair Options
Professional Repair (Recommended)
The 2023 Murano is covered by the factory warranty and the federal emissions warranty (8 years/80,000 miles). Take it to your Nissan dealer for no-cost diagnosis and repair.
DIY Repair
Not recommended on a warranty-age vehicle. Let the dealer handle it to preserve your coverage and avoid unnecessary expense.
Estimated Repair Costs
- Catalytic converter replacement: $650 - $1,500 (likely warranty-covered)
- Downstream O2 sensor: $125 - $300 (likely warranty-covered)
- ECM software update: $0 (warranty-covered)
- Exhaust leak repair: $100 - $400
Prevention Tips
- Use quality fuel as recommended
- Follow the dealer maintenance schedule
- Report check engine lights to the dealer promptly
- Avoid excessive short trips
- Keep all service records for warranty claims