What P0174 Means on Your 2024 Mazda CX-90
A P0174 code on your 2024 Mazda CX-90 means the engine control module has detected a lean air-fuel condition on Bank 2. The 2024 CX-90 is available with a 3.3L Skyactiv-G turbocharged inline-six engine producing 280 hp (or 340 hp in the PHEV variant) or a 3.3L Skyactiv-G turbo inline-six with mild-hybrid assist. As an inline-six, it has a single cylinder bank, but the ECU may flag Bank 2 when the lean correction range is exceeded.
The CX-90 is Mazda's flagship SUV, and the new inline-six is a significant engineering achievement. A lean condition on this engine needs prompt professional attention to protect this advanced powertrain.
Symptoms
- Check engine light on
- Rough or uneven idle
- Reduced power output and turbo response
- Decreased fuel economy
- Hesitation during acceleration
- Engine surging at steady speeds
Common Causes
- Boost Leak (35% likelihood) – The 3.3L turbo inline-six has a complex intake tract with multiple connections. Any leak after the MAF sensor introduces unmetered air and causes lean running.
- MAF Sensor Issue (25% likelihood) – Factory defect or contamination causing incorrect airflow readings.
- Fuel System Issue (25% likelihood) – Direct injection requires precise fuel pressure. A faulty injector or pump issue can restrict fuel delivery.
- Software Calibration (15% likelihood) – As a new engine platform, Mazda may release software updates to optimize fuel trim behavior.
Diagnosis
- Dealer visit – Your 2024 CX-90 is under warranty. The dealer has the Mazda-specific tools needed for this new engine.
- Check TSBs – The 3.3L inline-six is new, so TSBs may address known issues.
- Scan all codes – Review DTCs and freeze frame data.
- Boost leak test – Pressurize the intake to find leaks.
- Fuel pressure test – Verify against Mazda specifications.
Repair Costs
- Boost leak repair – $100–$450.
- MAF sensor – Cleaning: $10. Replacement: $130–$300.
- Fuel injector or pump – $350–$800 (higher due to six-cylinder configuration).
- Software update – Free under warranty.
Your 2024 CX-90 is covered by Mazda's 3-year/36,000-mile basic warranty and 5-year/60,000-mile powertrain warranty. All repairs should be covered at no cost.
Take It to the Dealer
The 2024 CX-90's 3.3L turbo inline-six is a brand-new engine platform. Dealer technicians have the proper training and Mazda-specific diagnostic equipment. Attempting DIY repairs on this engine could void warranty coverage. Let the dealer handle this one.
Prevention
- Follow Mazda's recommended service schedule
- Use quality fuel (premium recommended for turbo performance)
- Keep OEM air filtration components in place
- Report any drivability changes to your dealer promptly
- Keep up with software updates at dealer visits