P0204 on Mercedes-Benz: How to Diagnose & Fix
Injector Circuit/Open - Cylinder 4
2 Mercedes-Benz models · 2 documented issues · 2 critical · $300-$3,000 repair
P0204 on Mercedes-Benz by model: symptoms, diagnosis and fix
Sprinter diesel injectors develop seal failures leading to the "Black Death" condition where combustion gases leak past the injector copper washers, carbonizing and creating hard tar deposits around the injector bore. This is the most common and feared Sprinter repair, as advanced cases require expensive injector extraction procedures when the carbon welds the injectors in place.
Common Symptoms
- Black tar buildup around injectors visible under engine cover
- Ticking noise from engine
- Diesel smell in cab
- Rough idle
- Loss of power under load
How to Fix
Replace injector sealing washers and clean injector bores at the first sign of any leaking. If caught early this is a simple and inexpensive repair. Advanced cases with seized injectors may require specialized extraction tools or even cylinder head removal. Replace all injector washers simultaneously.
Owner tips & cautions
- WarningInspect your injector area at EVERY oil change. Black Death starts as a small seep and becomes catastrophic. A $20 copper washer replacement now prevents a $3,000 injector extraction later.
The OM651 diesel injectors in the GLK develop a condition known as "Black Death" where the copper injector sealing washers fail, allowing combustion gases to escape around the injector. The escaping gases carbonize and create hard black tar deposits around the injector bore, eventually welding the injector in place and making removal extremely difficult.
Common Symptoms
- Black tar deposits around diesel injectors
- Ticking noise from engine that changes with RPM
- Diesel smell in engine bay
- Rough idle
- Slight loss of power
How to Fix
Replace the injector sealing washers and clean the injector bores of carbon deposits. If caught early, this is a relatively simple repair. Advanced cases require specialized injector extraction tools and potentially new injectors. Replace all four injector washers simultaneously to prevent repeat failures.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Corteco OM651 fuel-injector sealing ring 6110170660OEMCorteco 6110170660
Technician-selected OM651 injector-seat repair stage using Mercedes-Benz 6110170660 Fitment/availability: The inspected direct U.S. page identifies Corteco 6110170660, explicitly catalogs GLK250 fitment, and showed availability, price an…
- Corteco OM651 repair-stage fuel-injector sealing ring 6110170760OEMCorteco 6110170760
Technician-selected later/thicker OM651 injector-seat repair stage using Mercedes-Benz 6110170760 Fitment/availability: The inspected FCP GLK250 catalog identifies Corteco 6110170760 for GLK250 and showed availability, price and purchase…
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Owner tips & cautions
- WarningInspect the injector area at every oil change. If you see any black deposits forming around the injectors, replace the copper washers immediately. Waiting turns a $200 repair into a $2,000 nightmare.
P0204 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0204 mean on a Mercedes-Benz?
P0204 stands for "Injector Circuit/Open - Cylinder 4." This code means the Engine Control Module detected an electrical problem (open circuit or out-of-range resistance) in the fuel injector control circuit for cylinder 4. The ECM controls each injector through its own circuit and monitors it to confirm proper operation. P0204 indicates the computer isn't seeing the expected electrical response from cylinder 4's injector, so that cylinder may not be getting the correct fuel. You'll often notice a misfire, rough running, and a loss of power tied to cylinder 4. On Mercedes-Benz it is documented across 2 models: Sprinter, GLK-Class.
What are the most common causes of P0204?
The most common causes of P0204 are: Damaged or corroded injector connector at cylinder 4, Open or shorted wiring in the injector control circuit, Failed (electrically open) fuel injector on cylinder 4, Loose or backed-out connector pin, Poor ground or power feed to the injector, Faulty injector driver inside the ECM/PCM, Chafed harness causing intermittent open. The specific cause varies by vehicle.
How much does it cost to fix P0204 on a Mercedes-Benz?
Published repair estimates on Mercedes-Benz range from $300 to $3,000 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0204 on a different make?
View P0204 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.