What Does P0172 Mean on Your 2024 Infiniti Q50?
A P0172 code on your 2024 Infiniti Q50 indicates the ECM has detected a rich air-fuel mixture on Bank 1. The 2024 Q50 features the VR30DDTT 3.0-liter twin-turbocharged V6, available in 300 hp and 400 hp (Red Sport 400) configurations, with a 7-speed automatic transmission. Bank 1 is the cylinder bank containing cylinder number 1.
Running rich means the air-fuel ratio has shifted toward excess fuel. The ECM uses oxygen sensor data to control fuel delivery and sets P0172 when it cannot maintain the proper 14.7:1 ratio on Bank 1.
Symptoms You May Notice
- Check engine light on
- Reduced fuel economy
- Rough idle
- Black exhaust smoke
- Fuel smell from exhaust
- Reduced turbo performance
- Bank 1 misfires
Common Causes of P0172 on the 2024 Infiniti Q50
- Contaminated MAF Sensor - Oil vapor from the twin-turbo system coats the MAF element, causing underreporting of airflow and over-fueling.
- Boost System Leak - Multiple charge pipe connections in the twin-turbo system can develop leaks.
- Leaking Direct Fuel Injector - High-pressure injectors on Bank 1 can develop leaks.
- Degraded Bank 1 O2 Sensor - A slow-responding upstream O2 sensor causes incorrect fuel calculations.
How to Diagnose P0172
- Scan all codes - Check for companion codes.
- Review fuel trims - Compare Bank 1 and Bank 2 LTFT.
- Clean the MAF - Best first step.
- Boost leak test - Check all connections.
- Monitor O2 sensors - Check Bank 1 response.
- Test injectors - Check Bank 1 for leaks.
Repair Options and Cost Breakdown
- MAF Cleaning - $15-$30 DIY.
- MAF Replacement - $190-$410 parts and labor.
- Boost Pipe Repair - $120-$460 depending on component.
- Fuel Injector Replacement - $360-$770 per injector.
- O2 Sensor Replacement - $230-$440 parts and labor.
Most repairs cost $200 to $520. Warranty coverage may apply for the 2024 model year.
Can You DIY This Repair?
MAF cleaning is the main DIY-friendly repair. The Q50 engine bay is tight with the twin-turbo setup, but basic access is possible. Boost hose inspection is feasible. Injector and turbo work require professional tools and expertise.
Prevention Tips
- Replace the air filter every 15,000-20,000 miles
- Use premium 91+ octane fuel
- Add fuel system cleaner every 10,000 miles
- Have the turbo system inspected during routine service
- Address check engine lights promptly