P0420 Code on Your 2022 Infiniti QX60: A Complete Guide
The 2022 Infiniti QX60 was completely redesigned for that model year, featuring a new 3.5L naturally aspirated V6 engine (VQ35DD) producing 295 horsepower paired with a 9-speed automatic transmission. If your QX60 is showing a P0420 code, the onboard diagnostics have determined that the Bank 1 catalytic converter is not converting exhaust pollutants as efficiently as required.
Bank 1 on the QX60's transverse-mounted V6 refers to the engine bank closest to the firewall (rear bank). Understanding this helps identify which catalytic converter is being flagged.
Symptoms to Look For
- Check engine light on — The most common indicator of a P0420 code
- Decreased fuel economy — You may notice a 1-3 MPG drop from your normal average
- Rotten egg smell from exhaust — Hydrogen sulfide odor when the catalyst material breaks down
- No obvious drivability changes — Many owners report the vehicle drives normally
- Emissions test failure — An active P0420 means automatic failure in emissions-testing states
Common Causes for the 2022 QX60
The 2022 QX60's 3.5L VQ35DD engine is generally reliable, but here are the most common causes of P0420:
- Catalytic converter degradation (40% likelihood) — The VQ35DD uses direct injection, which can produce higher exhaust particulates that stress the catalytic converter. Early degradation is possible especially with mixed driving conditions.
- Rear oxygen sensor malfunction (25% likelihood) — The Bank 1 downstream O2 sensor can fail or become contaminated, sending incorrect readings to the ECM.
- Exhaust leak at the manifold or flex pipe (20% likelihood) — The QX60's front-wheel-drive architecture places the exhaust manifolds in a tight space where heat cycling can cause gasket deterioration.
- Fuel system issue causing rich running (15% likelihood) — A leaking fuel injector or faulty fuel pressure regulator can cause excess fuel to enter the exhaust, overwhelming the catalytic converter.
Step-by-Step Diagnosis
Step 1: Full Diagnostic Scan
Use a quality OBD-II scanner to retrieve all codes. On Nissan/Infiniti vehicles, pay attention to any additional codes like P0420, P0430, P0136, P0156, or misfire codes that could indicate the root cause.
Step 2: Evaluate O2 Sensor Performance
With a scan tool capable of live data, monitor the Bank 1 upstream (sensor 1) and downstream (sensor 2) oxygen sensors. The upstream should oscillate between 0.1V and 0.9V rapidly. The downstream should hold relatively steady. If both sensors show similar patterns, the converter has lost its storage capacity.
Step 3: Check for Exhaust Leaks
Inspect the exhaust manifold, flex pipe, and catalytic converter connections for signs of leaks. The QX60's transverse engine layout means the rear bank exhaust is close to the firewall, making visual inspection challenging. A smoke test may be necessary.
Repair Options and Costs
The Infiniti QX60 is a premium midsize SUV, and parts tend to be moderately priced:
- Catalytic converter replacement: $1,400 - $2,600 (parts and labor). OEM Infiniti converters are recommended for proper fitment.
- Downstream O2 sensor replacement: $180 - $350 (parts and labor)
- Exhaust leak repair: $150 - $450 depending on location
- Fuel injector replacement: $300 - $600 for one or more injectors
Can You Fix This Yourself?
The downstream O2 sensor on the 2022 QX60 is moderately accessible from underneath the vehicle. With an O2 sensor socket and penetrating oil, a handy DIYer can tackle this job. Catalytic converter replacement requires professional tools and expertise, especially on the rear bank where space is limited.
Prevention Tips
- Use top-tier gasoline — Premium fuel is recommended for the QX60 and helps keep combustion clean
- Keep up with oil changes — Use the recommended 0W-20 synthetic oil at proper intervals
- Address misfires immediately — Unburned fuel from misfires can destroy catalytic converters quickly
- Take longer drives periodically — Highway driving helps the catalytic converter reach optimal temperature and burn off deposits