What Does P0174 Mean on Your 2020 Mercedes-Benz GLE?
A P0174 code on your 2020 Mercedes-Benz GLE (W167) tells you that Bank 2 of the engine is running too lean. The 2020 GLE 450 uses the M256 3.0L turbocharged inline-six, while the GLE 350 uses the M264 2.0L turbo-four. At 40,000-70,000 miles, wear-related issues are the primary concern.
Symptoms You Might Notice
- Check engine light on
- Rough idle or idle hunting
- Loss of power and boost
- Reduced fuel economy
- Hesitation under acceleration
- Hissing sounds from the engine bay
Common Causes of P0174 on the 2020 GLE
At this mileage, expect these potential culprits:
- Boost Leak — Aging charge pipe connections and intercooler hoses can develop leaks from years of boost cycling.
- Intake Manifold Gasket — Gaskets degrade over time, allowing unmetered air into the intake.
- Carbon Buildup — Direct-injection engines accumulate carbon on intake valves, affecting air metering by 50,000+ miles.
- Fuel System Wear — High-pressure fuel pump and injectors may show reduced performance at higher mileage.
How to Diagnose the Problem
- Scan all codes with Mercedes-compatible diagnostics.
- Monitor fuel trim adaptations — above +10% confirms lean.
- Inspect all boost connections and charge pipes for aging.
- Check intake manifold gaskets for leaks.
- Smoke test the complete boost and intake system.
- Test fuel pressure and injector balance.
Repair Options and Estimated Costs
- Boost leak repair: $250–$650.
- Intake manifold gasket: $350–$750.
- Carbon cleaning (walnut blasting): $450–$900.
- Fuel system service: $550–$1,300.
Can You Still Drive?
Drive gently. Your 2020 GLE is likely out of the standard warranty. Find a reputable independent Mercedes specialist — they typically charge 30-50% less than the dealer with comparable expertise.
Prevention Tips
- Schedule carbon cleaning around 50,000-60,000 miles.
- Use premium fuel exclusively.
- Maintain a strict service schedule.
- Inspect boost system components during regular service.
- Build a relationship with a trusted independent Mercedes shop.