P0203: Injector Circuit/Open - Cylinder 3
13 vehicles · 10 makes · $30-$5,000 repair
Most Reported On
P0203 is an OBD-II diagnostic trouble code meaning “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. This code is most commonly reported on 2010-2025 Mercedes-Benz Sprinter (Sprinter 1500, Sprinter 2500, Sprinter 3500, Sprinter 4500), 2017-2023 Ford Transit, and 2010-2015 Mercedes-Benz GLK-Class (GLK220 CDI, GLK250 BlueTEC), plus 10 other vehicles, with repair costs ranging from $30 to $5,000.
Common Causes
Typical Repair Cost
Based on 14 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose P0203, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
- Read & clear engine codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X OBD-II Scanner
by LAUNCH
A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
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Vehicles Affected (13)
FAQ
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 $5,000, depending on the vehicle and root cause.
Which vehicles are affected by P0203?
Au7o has documented P0203 across 13 vehicle models from 10 manufacturers: Chevrolet, Chrysler, Dacia, Ford, GMC, Land Rover, Mercedes-Benz, SEAT, Skoda, Volkswagen.
Sources (12)
- ForumFord Transit USA Forum Thread: Fuel Injector Issues on 2.0L EcoBlue Diesel
- videoEricTheCarGuy - Diagnosing and Replacing Fuel Injectors on Ford Transit 2.0L EcoBlue Diesel
- mediaDuramax LML CP4 Pump Problems - Merchant Automotive
- mediaHow to Prevent LML CP4 Failure - Dirty Diesel Customs
- ForumCP4 failure - DuramaxForum
- videoHow to Diagnose and Replace 7.3L Powerstroke Injectors - EricTheCarGuy
- videoYouTube - ChrisFix: How to Clean Fuel Injectors on an Older Car
- articleTd5 Injector Harness Explained: Symptoms, Causes & Replacement Guide — JGS4x4
- ForumTD5 Oil in the injector loom fault? — LR UK Forums
- articleResolving Injector Issues in the Land Rover Defender TD5 — Stedmans Garage
- manufacturerOregon Fuel Injection: Chevrolet-GMC Diesel Diagnostics
- ForumSilveradoSierra: 6.6L Duramax Diesel blowing white smoke
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.