What Does P0172 Mean on Your 2024 Infiniti QX80?
A P0172 code on your 2024 Infiniti QX80 indicates the ECM has detected a rich air-fuel mixture on Bank 1. The 2024 QX80 was redesigned and features a new 3.5-liter twin-turbocharged V6 producing 450 horsepower, replacing the previous 5.6L V8. It is paired with a 9-speed automatic transmission. Bank 1 is the cylinder bank containing cylinder number 1.
The new twin-turbo V6 uses direct injection and forced induction. Running rich means excess fuel in the combustion mixture, which reduces fuel economy and can damage the catalytic converter over time.
Symptoms You May Notice
- Check engine light on
- Fuel economy below the rated 18/22 mpg
- Rough idle
- Black exhaust smoke
- Fuel smell from exhaust
- Turbo lag or reduced power
- Bank 1 misfires
Common Causes of P0172 on the 2024 Infiniti QX80
- Dirty MAF Sensor - Oil vapor from the twin-turbo system can contaminate the MAF sensor, causing inaccurate airflow readings and over-fueling.
- Boost System Leak - The twin-turbo charge piping has multiple connection points where leaks can develop, reducing actual airflow.
- Leaking Direct Fuel Injector - High-pressure injectors on Bank 1 can develop leaks.
- 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, boost, MAF, and O2 companion codes.
- Review fuel trims - Compare Bank 1 and Bank 2 LTFT values.
- Clean the MAF - Best first step.
- Boost leak test - Check all charge pipe 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 - $200-$430 parts and labor.
- Boost Pipe Repair - $130-$500 depending on the component.
- Fuel Injector Replacement - $380-$800 per injector.
- O2 Sensor Replacement - $240-$460 parts and labor.
Most repairs cost $220 to $560. The 2024 QX80 is a premium flagship SUV with correspondingly higher parts costs. Warranty coverage likely applies for the new model.
Can You DIY This Repair?
MAF cleaning is the main DIY task. The redesigned 2024 QX80 engine bay may be less familiar to home mechanics. Boost hose inspection is feasible. Twin-turbo and injector work should be handled by an Infiniti specialist with proper diagnostic tools.
Prevention Tips
- Replace the air filter at recommended intervals
- Use premium 91+ octane fuel as recommended
- Add fuel system cleaner every 10,000 miles
- Have the turbo system inspected during scheduled service
- Address check engine lights promptly