What Does P0172 Mean on Your 2022 Infiniti Q50?
A P0172 code on your 2022 Infiniti Q50 means the ECM has detected that Bank 1 is running richer than the target air-fuel ratio. The 2022 Q50 is powered by a 3.0-liter twin-turbocharged V6 (VR30DDTT) producing either 300 hp in the Luxe trim or 400 hp in the Red Sport 400. Bank 1 is the cylinder bank containing cylinder number 1.
The VR30DDTT is a direct-injection twin-turbo engine known for its performance. Running rich means excess fuel is being delivered to Bank 1, which reduces efficiency and can damage the catalytic converter.
Symptoms You May Notice
- Check engine light on
- Fuel economy below the rated 20/29 mpg (300 hp) or 19/27 mpg (Red Sport)
- Rough idle
- Black exhaust smoke
- Fuel smell from the exhaust
- Reduced power or turbo lag
- Bank 1 misfires
Common Causes of P0172 on the 2022 Infiniti Q50
- Dirty MAF Sensor - Oil vapor from the twin-turbo system contaminates the MAF sensor, causing it to underreport airflow and trigger over-fueling.
- Boost System Leak - The twin-turbo charge piping and intercooler system have multiple connection points where leaks can develop.
- Leaking Direct Fuel Injector on Bank 1 - The VR30 uses high-pressure direct injection. A leaking injector adds unmetered fuel.
- Failing Bank 1 O2 Sensor - A degraded upstream oxygen sensor provides incorrect feedback to the ECM.
How to Diagnose P0172
- Scan all codes - Check for P0175 (Bank 2 rich), boost, MAF, and O2 companion codes.
- Review fuel trims - Compare Bank 1 and Bank 2 LTFT values. Bank 1 only being negative points to a bank-specific cause.
- Clean the MAF - The cheapest first step.
- Boost leak test - Pressurize the intake system.
- Monitor O2 sensors - Check Bank 1 Sensor 1 response.
- Test injectors - Check Bank 1 for leaks and balance.
Repair Options and Cost Breakdown
- MAF Cleaning - $15-$30 DIY.
- MAF Replacement - $180-$400 parts and labor.
- Boost Pipe Repair - $120-$450 depending on the component.
- Fuel Injector Replacement - $350-$750 per injector.
- O2 Sensor Replacement - $220-$430 parts and labor.
Most P0172 repairs on the Q50 cost between $200 and $500. The Q50 is an affordable luxury sedan with reasonable parts costs.
Can You DIY This Repair?
MAF cleaning is an easy DIY task. The Q50 engine bay is tight with the twin-turbo setup, but basic inspections are possible. Boost hose connections can be checked at home. Fuel injector and turbo system work requires professional expertise and tools.
Prevention Tips
- Replace the air filter every 15,000-20,000 miles
- Use premium 91+ octane fuel as recommended
- Add fuel system cleaner every 10,000 miles
- Have the turbo system inspected during routine service
- Address check engine lights promptly