P0175 on the 2021 Ford Bronco Sport
The P0175 code on your 2021 Ford Bronco Sport indicates a rich fuel condition detected by the PCM. The Bronco Sport is available with two EcoBoost engine options: the 1.5L three-cylinder (181 hp) in base through Outer Banks trims, and the 2.0L four-cylinder (250 hp) in the Badlands and First Edition trims. Both are turbocharged with direct injection, but the three-cylinder and four-cylinder have different diagnostic nuances.
Compact SUV, Capable Engines
Unlike the full-size Bronco, the Bronco Sport is based on the C2 platform shared with the Escape. The engines are transverse-mounted with front-wheel or all-wheel drive. The compact engine bay means components are tightly packaged, which can affect heat management around sensors. The Bronco Sport's trail capability also means these vehicles see occasional off-road use that exposes the intake and exhaust to dust and water.
Symptoms
- Check engine light illuminated
- Fuel economy below the rated 25/28 MPG (1.5L) or 24/28 MPG (2.0L)
- Engine vibration at idle (especially noticeable on the three-cylinder)
- Dark exhaust emissions
- Reduced throttle response or turbo hesitation
- Fuel smell from exhaust
Top Causes
1. MAF Sensor Contamination
Both Bronco Sport engines use a MAF sensor before the turbo inlet. The Bronco Sport's adventure-oriented use means trails, dirt roads, and beach driving can introduce dust to the sensor. PCV system blow-by during normal operation also contributes. Cleaning the MAF sensor is the first diagnostic step and costs virtually nothing.
2. O2 Sensor Degradation
At 30,000-50,000 miles on a 2021 model, the upstream O2 sensor may show early wear from turbo exhaust heat. The three-cylinder 1.5L produces wider exhaust pulses that create different thermal patterns at the sensor compared to a four-cylinder. A degraded sensor provides slow or biased feedback, causing the PCM to over-fuel.
3. Direct Injector Leak
On the 1.5L three-cylinder, a single leaking injector represents 33% of fuel delivery, making the impact severe. On the 2.0L four-cylinder, it is 25%. In either case, an injector that does not seal adds unmetered fuel to the combustion chamber. Check for companion misfire codes to identify the affected cylinder.
4. Boost System Leak
The turbo charge air system on both engines includes intercooler piping and silicone couplers. Trail vibration and the thermal cycling of on-off-road transitions can loosen connections. A boost leak creates a discrepancy between measured and actual cylinder air, resulting in a rich mixture.
Diagnostic Process
- Identify your engine (1.5L three-cylinder or 2.0L four-cylinder)
- Scan for all codes including boost and misfire companion codes
- Monitor fuel trims at idle and under boost
- Clean the MAF sensor with dedicated spray
- Inspect charge air system connections for leaks
- Test the upstream O2 sensor response with live data
- Check for misfire codes pointing to a specific injector
- Verify fuel pressure at the direct injection rail
Repair Costs
MAF cleaning: under $15. O2 sensor: $160-$340. Direct injector: $280-$700 per injector. Boost system repair: $50-$250. The 2021 Bronco Sport is under Ford's 5-year/60,000-mile powertrain warranty through 2026, and many repairs should be covered.
Priority Level
Fix P0175 within two to three weeks. The compact engines in the Bronco Sport are more sensitive to fuel mixture imbalances than larger engines. Running rich accelerates oil dilution in small displacement engines and puts the smaller catalytic converter at risk. If you use the Bronco Sport for trail activities, full engine power is essential for off-road capability.