What Does P0172 Mean on Your 2024 Mercedes-Benz GLE?
A P0172 code on your 2024 Mercedes-Benz GLE (W167) means the engine management system has detected that Bank 1 is running too rich. The 2024 GLE 350 uses the M254 2.0-liter turbocharged four-cylinder with 255 horsepower, while the GLE 450 features the M256 3.0-liter turbocharged inline-six with EQ Boost producing 375 horsepower. Both engines use direct fuel injection and 48-volt mild-hybrid technology.
The GLE is a premium midsize SUV, and repairs reflect its luxury status. A rich condition should be resolved quickly to avoid expensive turbocharger and catalytic converter damage.
Symptoms You Might Notice
- Check engine light on the MBUX display
- Reduced fuel efficiency
- Black exhaust smoke, especially under load
- Fuel smell at the tailpipe
- Rough or uneven idle
- Reduced power or turbo boost
Common Causes of P0172 on the 2024 GLE
- Contaminated MAF Sensor - The hot-film mass airflow sensor is sensitive to oil mist and environmental contamination. When it under-reads airflow, the ECU over-fuels the engine.
- Leaking Direct Fuel Injector - High-pressure injectors on both the M254 and M256 engines can develop seal issues or carbon deposits, causing excess fuel delivery.
- Crankcase Ventilation System Fault - The CCV system can malfunction even on newer vehicles, allowing excess oil vapors into the intake manifold.
- Boost Pressure or Wastegate Issue - A faulty boost pressure sensor or wastegate actuator on the turbo can cause fuel delivery miscalculation during boost conditions.
How to Diagnose the Problem
Use Mercedes Xentry or a compatible diagnostic tool. Read fault codes and fuel adaptation values. Negative multiplicative fuel corrections on Bank 1 confirm the rich condition. Check for additional turbo-related or sensor codes.
Inspect the air filter and clean the MAF sensor. Check the intake for oil residue. Test boost pressure accuracy with the diagnostic tool. If adaptations remain out of range, perform injector and lambda sensor testing. The 2024 GLE is under warranty, so dealer diagnosis is recommended.
Repair Options and Cost Breakdown
- Air filter replacement - $35 to $70.
- MAF sensor cleaning or replacement - $15 to $480.
- Lambda sensor replacement - $300 to $550.
- Direct fuel injector replacement - $500 to $1,100.
- Crankcase ventilation valve replacement - $280 to $550.
Prevention Tips
Use premium fuel as required and Mercedes-approved synthetic oil. Follow the maintenance schedule strictly. The M256 inline-six benefits from periodic intake valve cleaning and fuel system maintenance. Monitor fuel economy as an early indicator of fuel system issues. Catalytic converter replacement on the GLE can exceed $2,500, making preventive care a worthwhile investment.