What Does P0172 Mean on Your 2022 Lincoln Navigator?
A P0172 code on your 2022 Lincoln Navigator means the engine control module (PCM) has detected a rich air-fuel mixture on Bank 1. The 2022 Navigator is powered by a 3.5-liter twin-turbocharged V6 EcoBoost engine producing 440 horsepower, paired with a 10-speed automatic transmission. Bank 1 is the cylinder bank containing cylinder number 1, which on the 3.5L EcoBoost is the passenger-side bank.
Running rich means there is too much fuel in the combustion mixture. The twin-turbo system adds complexity because boost pressure directly affects fuel delivery calculations.
Symptoms You May Notice
- Check engine light on
- Fuel economy worse than the rated 16/22 mpg
- Rough or shaky idle
- Black exhaust smoke on acceleration
- Strong fuel smell from the exhaust
- Reduced power or turbo lag
- Possible misfires on Bank 1 cylinders
Common Causes of P0172 on the 2022 Lincoln Navigator
- Dirty MAF Sensor - The EcoBoost engine's MAF sensor is prone to contamination from oil vapor in the turbo inlet. A dirty MAF underreads airflow and causes over-fueling.
- Boost System Leak - The twin-turbo system uses extensive charge piping and intercoolers. Any leak in this pressurized path reduces actual airflow.
- Leaking Fuel Injector on Bank 1 - The direct injection system operates at extreme pressures. A leaking injector adds unmetered fuel to the cylinder.
- Failing Bank 1 Upstream O2 Sensor - A degraded oxygen sensor on Bank 1 provides incorrect feedback to the PCM.
How to Diagnose P0172
- Scan all codes - Check for P0175 (Bank 2 rich), boost codes, MAF codes, or O2 sensor codes.
- Review fuel trims - Compare Bank 1 and Bank 2 LTFT values. Bank 1 only being negative points to a bank-specific cause.
- Clean the MAF sensor - The cheapest and most effective first step.
- Boost leak test - Pressurize the intake system and check all connections on the twin-turbo system.
- Monitor O2 sensors - Check Bank 1 Sensor 1 response time.
- Test fuel injectors - Check injector balance and leak-down on Bank 1.
Repair Options and Cost Breakdown
- MAF Sensor Cleaning - $15-$30 for spray cleaner. Easy DIY.
- MAF Sensor Replacement - $180-$400 parts and labor.
- Boost Pipe or Connection Repair - $120-$500 depending on the component. Twin-turbo systems have many connections.
- Fuel Injector Replacement - $350-$750 per injector with labor.
- O2 Sensor Replacement - $220-$420 parts and labor.
Most P0172 repairs on the Navigator cost between $200 and $550. The Navigator is a premium full-size SUV, but the EcoBoost engine shares many parts with the Ford F-150 and Expedition.
Can You DIY This Repair?
MAF sensor cleaning is an easy DIY job even on the Navigator. The engine bay is spacious. Boost hose inspection is manageable. However, the twin-turbo direct injection system is complex, and injector or turbo work should be handled by a Ford/Lincoln specialist with proper diagnostic tools.
Prevention Tips
- Replace the engine air filter every 15,000-20,000 miles
- Use quality 87+ octane fuel from top-tier stations
- Add fuel system cleaner every 10,000 miles
- Have the turbo and boost system inspected during routine service
- Address check engine lights promptly to protect the catalytic converters