P0203: How to Diagnose & Fix — Injector Circuit/Open - Cylinder 3
16 vehicles · 11 makes · $30-$6,500 repair
How to diagnose and fix P0203: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Mercedes-Benz Sprinter · 2010–2025
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.
Ford Transit · 2017–2023
The 2017-2023 Ford Transit with the 2.0L EcoBlue diesel engine (available in some markets) and the 3.5L EcoBoost V6 experience fuel injector failures causing rough running, misfires, poor idle, reduced performance, and excessive smoke on cold start. Parkers UK documents an official Ford service action for Transit EcoBlue diesel injector failures traced to a quality issue with Continental-supplied injectors where an internal surface coating comes unstuck, blocking the injector. FordTransitUSAForum.com documents injector failure on 3.5L EcoBoost Transit models as well, where direct injection fuel deposits cause injector spray pattern degradation. RepairPal estimates individual injector replacement between $266 and $627 depending on Transit model, but multiple injectors often need replacement simultaneously, and contaminated fuel systems can cost significantly more.
Common Symptoms
- Rough running and engine misfires
- Poor idle quality
- Excessive blue or black smoke on cold start
- Reduced engine performance and power
- Check engine light with injector or misfire codes
- Engine stalls immediately after starting
- High fuel consumption
- Engine hesitation under acceleration
How to Fix
For Transit 3.5L EcoBoost: replace failed injectors ($100-200 per injector, 3-4 hours labor). Consider replacing all 6 injectors if the vehicle has over 100k miles - if one has failed, others are likely close behind. For EcoBlue diesel: Ford issued a service action for Continental injector failures - check with dealer for coverage. Use only Top Tier gasoline and change fuel filters per schedule. Professional fuel system cleaning every 50,000 miles can extend injector life.
Sources for this issue (1)
Mercedes-Benz GLK-Class · 2010–2015
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.
Chevrolet Silverado 2500HD · 2001–2015
GMC Sierra 2500HD · 2001–2004
Find P0203 by make
Browse every documented model and issue for your make.
P0203 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 P0203 mean?
P0203 stands for "Injector Circuit/Open - Cylinder 3." 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 3. The ECM pulses each injector electrically and watches the circuit to verify it is operating. P0203 means the expected feedback for cylinder 3's injector is missing or abnormal, so that cylinder may not be fueling properly. The typical result is a misfire, rough idle, and reduced performance traceable to cylinder 3.
What are the most common causes of P0203?
The most common causes of P0203 are: Damaged or corroded injector connector at cylinder 3, Open or shorted wiring in the injector control circuit, Failed (electrically open) fuel injector on cylinder 3, 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 P0203?
Repair costs for P0203 range from $30 to $6,500, depending on the vehicle and root cause.
Which vehicles are affected by P0203?
Au7o has documented P0203 across 16 vehicle models from 11 manufacturers: Audi, Chevrolet, Chrysler, Dacia, Ford, GMC, Land Rover, Mercedes-Benz, SEAT, Skoda, Volkswagen.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.