Cracking the P0440 Case on Your 2022 Mercedes-Benz C-Class
A P0440 on your 2022 Mercedes-Benz C-Class (W206) signals an EVAP system malfunction. The all-new W206 C 300 features a 2.0L turbo with EQ Boost mild-hybrid (255 hp) and 9G-TRONIC automatic. Mercedes's EVAP system includes a leak detection pump for self-diagnostics. With a few years of service, certain components may need attention. Let's investigate.
Symptoms
- Check engine light on
- Faint fuel odor
- Slight MPG decrease
- Fueling difficulties
- Emissions test failure
Your C-Class drives normally. Engine, 9G-TRONIC, and 4MATIC are unaffected.
Most Likely Causes
- Fuel Filler Seal — Worn or not properly seated. Estimated repair: $5–$35.
- Leak Detection Pump (LDP) — Mercedes's EVAP diagnostic pump. Known failure point. Estimated repair: $155–$370.
- Purge Valve (Regeneration Valve) — Controls vapor flow to the engine. Estimated repair: $115–$280.
- Shut-Off Valve — Controls EVAP venting near the canister. Estimated repair: $125–$300.
- EVAP Hose Leak — Small cracks in vapor lines. Estimated repair: $55–$165.
Diagnostic Steps
- Check fuel filler, clear code, drive 50+ miles
- Scan with Mercedes XENTRY or Star Diagnostic
- Test leak detection pump operation
- Test purge and shut-off valves
- Smoke test the system
Repair Costs
- Fuel filler: $5–$35
- LDP: $155–$370
- Purge valve: $115–$280
- Shut-off valve: $125–$300
- EVAP hose: $55–$165
- Diagnostic: $100–$185
Warranty: Check your mileage — Mercedes's 4-year/50,000-mile warranty may still apply.
Can I Drive With P0440?
Yes. No performance or safety impact.
DIY Feasibility
Mercedes EVAP repairs are moderate DIY difficulty. The LDP and purge valve are accessible but require Mercedes-specific diagnostics. Independent Mercedes shops offer 25-35% savings over dealers for out-of-warranty repairs.