P0456 on MERCEDES-BENZ C-CLASS
EVAP System Leak Detected (very small leak)
Methodology: Reviewed against the SAE J2012 generic DTC definition and NHTSA owner-complaint patterns, then scoped to Mercedes Benz C Class context without treating complaints as confirmed diagnoses.
Sources: SAE/OBD-II definitions, manufacturer service information, and public reliability reports (including NHTSA where applicable).
- SAE J2012 Diagnostic Trouble Code Definitions — Generic diagnostic trouble code definition reference for P0456.
- NHTSA recalls, complaints, and manufacturer communications — Used to check public owner complaint context, recall status, and safety-related manufacturer communications by VIN or vehicle.
Limits: Guidance is informational and may not match every model-year or revision. Confirm with the official manual and diagnostics before replacing parts. For safety-critical or electrical work, use a qualified technician.
What P0456 Means on Your MERCEDES-BENZ C-CLASS
P0456 is a diagnostic trouble code indicating: EVAP System Leak Detected (very small leak). This code relates to the powertrain, fuel, ignition, emissions, or air-management system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.
Real MERCEDES-BENZ C-CLASS Owner Reports
Source: NHTSA Complaints Database
"My engine light jeep coming on with a p0456 code. replace gas cap and purge valve control less then year ago. however i still smell gas when i fill up tank. after it goes down to 3/4 tank i don't smell gas. when it drop below half tank the engine light comes on."
"When fuel tank is about 75%-100% full, the car will smell heavily of gasoline inside and around the rear of the vehicle. upon inspection, fuel pump cover/cap seems to be cracked and leaking fuel. engine code p0456."
All reports filed by vehicle owners directly with the U.S. Department of Transportation.
📊 Complaint Trend by Model Year
Common Causes on MERCEDES-BENZ C-CLASS
Based on NHTSA complaint component analysis for this vehicle.
What To Do Next
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1
Check for recalls on YOUR VIN
Go to nhtsa.gov/recalls and enter your VIN. If your vehicle is covered, repairs are free.
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2
Get a proper diagnosis
A code alone doesn't tell you the exact failed part. A diagnostic at a shop ($50–$150) pinpoints the root cause before you spend money on parts.
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3
Compare repair quotes
Get 2–3 quotes. Dealer vs. independent shop prices often differ 30–50% for the same repair.