What Does P0174 Mean on Your 2024 Mercedes-Benz E-Class?
A P0174 code on your 2024 Mercedes-Benz E-Class (W214) indicates that the engine control unit has detected a lean air-fuel mixture on Bank 2. The 2024 E 300 uses the M254 2.0L turbocharged four-cylinder with a 48-volt integrated starter-generator (ISG), producing 255 horsepower with an additional electric boost.
Symptoms You Might Notice
- Check engine light illuminated on the dashboard
- Rough or unsteady idle
- Reduced acceleration and power
- Lower fuel economy
- Engine hesitation under load
- Possible hissing or whistling sounds
Common Causes of P0174 on the 2024 E-Class
The M254 engine features advanced turbocharging and mild hybrid technology. Common lean code causes include:
- Boost Leak — Charge pipes, intercooler connections, or turbo inlet seals can leak, especially under high boost conditions.
- Vacuum System Leak — Various vacuum-operated systems can develop leaks at hose connections or diaphragms.
- Fuel Injector Issue — A clogged or weak direct injector reduces fuel delivery to affected cylinders.
- MAF Sensor Defect — A manufacturing defect or contamination on the mass airflow sensor leads to metering errors.
How to Diagnose the Problem
- Scan with Mercedes Star Diagnostic or compatible tool for all codes.
- Monitor fuel trim adaptation values — above +10% confirms lean.
- Inspect all turbo piping and intercooler connections.
- Check vacuum hoses and connections throughout the engine bay.
- Smoke test the boost and intake system.
- Test fuel pressure and injector balance under load.
Repair Options and Estimated Costs
- Boost leak repair: $250–$650. Parts and labor costs vary.
- Vacuum leak repair: $150–$400.
- Fuel injector replacement: $550–$1,300. Requires Mercedes diagnostic tools.
- MAF sensor replacement: $220–$500.
Can You Still Drive?
Drive gently. Your 2024 E-Class is under Mercedes-Benz's warranty. Schedule a dealer appointment promptly to prevent any engine damage from running lean under boost.
Prevention Tips
- Utilize your Mercedes-Benz warranty for all powertrain concerns.
- Use premium fuel (91+ octane) as specified.
- Follow the Mercedes-Benz maintenance schedule strictly.
- Keep the engine air filter clean.
- Never ignore dashboard warning lights.