The 2020 Ford F-150 triggering P0172 indicates a rich condition on bank 1—too much fuel relative to air. America's best-selling truck offers multiple engine options, each with specific rich-condition causes to investigate.
Understanding P0172
P0172 indicates long-term fuel trim has reached approximately -25%, meaning the ECM consistently subtracts fuel to compensate for detected rich conditions. This points to excess fuel delivery or restricted air supply.
F-150 Engine Configurations
The 2020 F-150 offers 3.3L V6, 2.7L EcoBoost V6, 3.5L EcoBoost V6, 5.0L V8, and 3.0L diesel options. Bank 1 contains cylinder 1—typically the passenger side bank on V-configuration engines. Each engine has specific considerations.
Common Rich Causes
Leaking fuel injectors introduce excess fuel. A faulty MAF sensor may overreport airflow. Stuck-open fuel pressure regulator increases fuel delivery. Oxygen sensor failure can falsely report lean, causing ECM to add fuel. Engine oil in the intake from excessive blow-by enriches mixture.
Fuel Injector Testing
Check for leaking injectors by observing fuel rail pressure drop with the engine off. Perform injector balance testing to identify weak or stuck injectors. Visual inspection may reveal external leaks.
Oxygen Sensor Analysis
A failed upstream oxygen sensor stuck lean causes the ECM to continuously add fuel. Monitor sensor voltage—a functioning sensor oscillates between rich and lean. A stuck low voltage indicates potential sensor failure.
Repair Costs
Oxygen sensor replacement costs $150-350. Fuel injector replacement ranges $200-500 per injector. MAF sensor replacement runs $100-250. Fuel pressure regulator replacement costs $200-400.