⚠️ Mercedes-Benz manufacturer position
WIS tank module access from rear seat or boot on W205/W206. HV safety for PHEV before fuel work.
Vehicle information
| Make | Mercedes-Benz |
|---|---|
| Model | C-Class |
| Market status | Sold new in Great Britain — W206 (2021–present) |
| Body styles | Saloon, Estate, All-Terrain (limited UK) |
| Generations | W204, W205, W206 (current UK) |
| Engine options | Petrol: 2.0 L petrol (M254) and AMG petrol on UK trims Diesel: 2.0 diesel OM654 on UK diesel C-Class Hybrid: C 300 e plug-in hybrid — petrol tank with HV battery |
| Fuel tank capacity | Approximately 50–66 litres depending on variant |
| Fuel system | Direct-injection petrol; OM654 common-rail diesel; PHEV isolated HV procedures |
| Access method | Rear seat / boot floor access typical — verify in WIS |
| Anti-siphon | Yes |
| Service portal | Mercedes-Benz WIS / XENTRY Workshop (authorised dealers) |
Misfuel risk High
Diesel variants use common-rail injection at very high pressure; petrol in diesel destroys pump lubrication and can contaminate the entire fuel circuit within seconds of running. PHEV still uses petrol — do not add diesel.
If the engine was not started
Drain, filter, correct fuel; PHEV: HV off per workshop manual.
If the engine was started
Diesel contamination after running: full HP circuit evaluation.
Access procedure
- Disconnect the negative battery terminal and relieve fuel system pressure per OEM procedure.
- Access the in-tank fuel pump module via the manufacturer-specified route (access panel or tank lowering).
- Drain contaminated fuel using approved recovery equipment into suitable containers for hazardous waste duty of care.
- Inspect the tank, sender unit, and lines; replace the fuel filter and any contaminated flexible lines as required.
- Reassemble, refill with the correct fuel grade, prime the low-pressure circuit, and check for leaks before start.
- If the engine was run on wrong fuel, follow OEM guidance for high-pressure pump, rail, and injector inspection before restart.
Frequently asked questions
What should I do if I put petrol in my Mercedes-Benz C-Class diesel?
Do not start the engine. Arrange OEM-method tank fuel extraction and hazardous waste disposal under UK duty of care. A GBIFDA-certified technician can document the procedure for insurers.
Does Mercedes-Benz warranty cover misfuel on a C-Class?
Manufacturer warranties typically exclude wrong fuel as misuse. Expect out-of-pocket or insurance-funded repair.
Can I siphon fuel from a Mercedes-Benz C-Class?
UK Mercedes-Benz models usually have anti-siphon filler necks; OEM information specifies pump-module or tank removal instead.
When are injectors replaced after misfuel on a C-Class?
If the engine ran on contaminated diesel, injectors and HP pump are inspected or replaced per Mercedes-Benz diagnostics; not always required if caught before start.
Need professional misfuel recovery?
Find a certified operator or read consumer guidance for your next steps.
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