What Does P0174 Mean on Your 2024 Mercedes-Benz C-Class?
A P0174 code on your 2024 Mercedes-Benz C-Class (W206) indicates that the engine control unit has detected a lean fuel condition on Bank 2. The 2024 C 300 uses the M254 2.0L turbocharged four-cylinder engine with a 48-volt mild hybrid system, producing 255 horsepower. A lean condition on this advanced powertrain needs professional attention.
Symptoms You Might Notice
- Check engine light (MIL) illuminated
- Rough or unsteady idle
- Reduced power and turbo boost
- Decreased fuel economy
- Hesitation during acceleration
- Possible hissing or whistling from the engine bay
Common Causes of P0174 on the 2024 C-Class
The M254 engine is Mercedes-Benz's latest four-cylinder turbo with advanced technologies:
- Boost Leak — Charge pipes, intercooler connections, or turbo inlet seals can develop leaks. Boost leaks are the leading cause of lean codes on turbo engines.
- Intake System Leak — A cracked intake manifold, loose connection, or deteriorating gasket can introduce unmetered air.
- Fuel Injector Issue — A clogged or underperforming direct injector reduces fuel delivery to affected cylinders.
- MAF Sensor Contamination — The mass airflow sensor can be affected by oil mist or debris, leading to incorrect readings.
How to Diagnose the Problem
- Scan with a Mercedes-compatible diagnostic tool (Xentry, iCarsoft, or similar).
- Monitor fuel trims — adaptation values exceeding +10% confirm lean running.
- Inspect charge pipes and intercooler connections for cracks or loose clamps.
- Check the intake manifold and all gaskets for leaks.
- Smoke test the entire boost and intake system.
- Test fuel pressure under load.
Repair Options and Estimated Costs
- Boost leak repair: $250–$600. Parts and labor vary by location.
- Intake manifold gasket: $300–$700. Professional repair recommended.
- Fuel injector replacement: $500–$1,200. Requires Mercedes diagnostic tools.
- MAF sensor replacement: $200–$450.
Can You Still Drive?
Drive gently and avoid heavy throttle. Your 2024 C-Class is under Mercedes-Benz's 4-year/50,000-mile warranty. Schedule a dealer appointment immediately.
Prevention Tips
- Use your Mercedes-Benz warranty for all engine codes while active.
- Use premium fuel (91+ octane) as required.
- Follow the Mercedes-Benz maintenance schedule.
- Keep the air filter fresh.
- Address any dashboard warnings immediately.