What Does P0172 Mean on Your 2022 Mercedes-Benz GLE?
When your 2022 Mercedes-Benz GLE (W167) sets a P0172 code, the engine management system has determined that Bank 1 is running too rich. The 2022 GLE 350 uses the M264 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 362 horsepower. Both engines use direct fuel injection and are highly sensitive to air-fuel ratio deviations.
With the 2022 model potentially approaching its warranty limits, diagnosing and fixing P0172 now is important for both vehicle longevity and to maximize any remaining warranty coverage.
Symptoms You Might Notice
- Check engine light on
- Increased fuel consumption
- Black or sooty exhaust smoke
- Fuel odor from the tailpipe
- Rough idle or engine vibration
- Reduced performance or turbo boost
Common Causes of P0172 on the 2022 GLE
- Dirty MAF Sensor - After a few years of service, the hot-film mass airflow sensor can accumulate contamination, leading to under-reading of airflow and over-fueling.
- Crankcase Ventilation Valve Deterioration - The CCV valve on Mercedes turbo engines can begin to fail, allowing excess oil vapors to enter the intake manifold.
- Leaking Direct Fuel Injector - High-pressure injectors can develop carbon deposits or seal wear, causing them to deliver more fuel than the ECU commands.
- Lambda Sensor Drift - The upstream wideband oxygen sensor can lose calibration over time, feeding inaccurate data to the ECU.
How to Diagnose the Problem
Use a Mercedes diagnostic tool to pull fault codes and review fuel adaptation values. Negative multiplicative corrections on Bank 1 confirm the rich condition. Check for companion codes and look for oil contamination in the intake system.
Start with air filter inspection and MAF sensor cleaning. Test the lambda sensor with live data. Check the CCV system for proper operation. If the code persists, perform injector diagnostics. Take advantage of any remaining warranty coverage for covered repairs.
Repair Options and Cost Breakdown
- Air filter replacement - $32 to $65.
- MAF sensor cleaning or replacement - $15 to $460.
- Crankcase ventilation valve replacement - $260 to $530.
- Lambda sensor replacement - $280 to $520.
- Direct fuel injector replacement - $480 to $1,050.
Prevention Tips
Premium fuel and Mercedes-approved oil are essential. Stay current with scheduled maintenance. The M256 inline-six benefits from periodic fuel system cleaning. Monitor fuel economy as an early warning system. If you notice oil consumption increasing, have the crankcase ventilation system checked proactively.