Your 2022 BMW X5's check engine light appeared with P0172—the engine is running rich (too much fuel relative to air). You've also noticed power loss, which seems counterintuitive for a "too much fuel" condition. Understanding how these connect helps you address the problem effectively.
What P0172 Means
P0172 indicates the Engine Control Module detected a rich condition on Bank 1—more fuel than the air-fuel mixture should contain. The ECM monitors oxygen sensors and adjusts fuel delivery, but when corrections exceed the system's ability to compensate, P0172 sets.
The 2022 X5 offers the B58 3.0L turbo six-cylinder, N63 4.4L twin-turbo V8, or M50i/M60i variants—all use direct injection and boost.
Why Rich Causes Power Loss
Excessive fuel doesn't burn completely, reducing combustion efficiency. The engine struggles to produce power from inefficient combustion.
The ECM may enter a protective mode, limiting power to prevent catalyst damage from unburned fuel.
Rich conditions can foul spark plugs, compounding the problem with misfires.
Common Causes
Fuel injector problems—sticking open, leaking, or over-delivering—inject excess fuel. Direct injectors on BMW engines can fail this way.
Mass airflow sensor reading low causes the ECM to undercalculate air, resulting in overfueling relative to actual airflow.
Fuel pressure too high forces excess fuel through injectors. Faulty fuel pressure regulator or returnless system issues can cause this.
EVAP purge valve stuck open introduces fuel vapor constantly, enriching the mixture beyond ECM correction ability.
Oxygen sensor failure reporting falsely lean causes the ECM to add fuel trying to correct a non-existent problem.
Diagnostic Approach
Monitor fuel trims with BMW ISTA or capable scan tool. High negative fuel trim (ECM removing fuel) confirms the system is fighting rich condition.
Check MAF sensor readings and compare to specifications at various RPMs.
Test fuel pressure for proper specification. Too high indicates pressure regulation problems.
Inspect spark plugs for carbon fouling or wet, fuel-smelling deposits indicating which cylinders run richest.
Test oxygen sensors for proper response and heating.
Repair Costs
MAF sensor: $150-$400 installed.
Fuel injector: $300-$700 per injector on direct injection systems.
Fuel pressure regulator: $200-$500 installed.
Oxygen sensor: $150-$400 per sensor.
EVAP purge valve: $100-$300.