What P0174 Means for Your 2021 Ford Bronco Sport
The P0174 code on your 2021 Ford Bronco Sport indicates that the engine is running lean on Bank 2. The 2021 Bronco Sport is available with a 1.5L EcoBoost turbocharged 3-cylinder engine in the base, Big Bend, and Outer Banks trims, or a 2.0L EcoBoost turbocharged 4-cylinder in the Badlands trim. Both engines use turbocharging and direct injection. A lean condition means the air-fuel ratio has too much air relative to fuel.
Symptoms to Watch For
- Check engine light on
- Rough or shaky idle
- Hesitation when accelerating
- Reduced power output
- Lower fuel economy
- Possible whistling noise from the engine bay area
Top Causes for the 2021 Bronco Sport
- Boost Leak (35% likelihood) - Both EcoBoost engines use pressurized turbo plumbing. Intercooler pipes, clamp connections, and charge air cooler hoses can develop leaks.
- MAF Sensor Contamination (25% likelihood) - A dirty MAF sensor is one of the most frequent causes of lean codes. Off-road dust exposure can contribute to this on the Bronco Sport.
- PCV System Issue (20% likelihood) - The 1.5L 3-cylinder engine's PCV system can develop leaks that create a vacuum leak and lean condition.
- Fuel Injector Problem (20% likelihood) - Direct injection fuel injectors can have flow issues, especially if low-quality fuel has been used.
Diagnosis Steps
- Scan all codes - Check for P0171 and other related codes to narrow the diagnosis.
- Boost pressure test - Pressurize the intake system and check for leaks.
- Test MAF sensor - The 1.5L should read about 4-6 g/s at idle; the 2.0L about 5-8 g/s. Clean the sensor first.
- Inspect PCV system - Check valve and hoses for leaks and proper operation.
- Monitor fuel trims - Long-term fuel trims above +10% confirm the lean condition.
Repair Cost Estimates
- Boost leak repair - $80 to $300.
- MAF sensor replacement - $120 to $280 with labor.
- PCV valve replacement - $60 to $175.
- Fuel injector service - $200 to $500 for cleaning; $300 to $600 for replacement.
Warranty Coverage
Your 2021 Bronco Sport should still be under the 5-year/60,000-mile powertrain warranty. Depending on mileage, the bumper-to-bumper warranty may also apply. Take it to a Ford dealer for a free diagnosis.
Prevention Tips
- Use OEM air filters, especially if driving in dusty conditions
- Clean the MAF sensor every 15,000 miles for off-road use
- Inspect boost pipe connections during oil changes
- Use Top Tier fuel for injector cleanliness
- Report any changes in engine performance to your dealer