P0203 — Injector Circuit Open Cylinder 3
What it means: Injector Circuit Open Cylinder 3.
How serious / can you keep driving: Serious. Power derate likely — plan to stop soon.
Check first: Measure injector resistance
Don't risk it — look up listed providers near you and give them this code when you call.
Listed providers nearest Louisville, KY
Closest first. Tell them P0203 and what the truck is doing. RoadService.app lists these providers and does not employ them or carry out the repair.
- 0.0 mi away — based in Louisville, KY · (502) 773-1159
- 0.0 mi away — based in Louisville, KY · (502) 447-1234
- 0.0 mi away — based in Louisville, KY · (502) 648-6725
Seen on: Heavy Truck/Diesel
What P0203 means
Injector Circuit Open Cylinder 3. Common causes: Failed injector solenoid.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- Failed injector solenoid
- Broken wiring
- corroded connector
First moves (roadside)
- Measure injector resistance
- check harness continuity
FAQ
Injector Circuit Open Cylinder 3. Common causes: Failed injector solenoid.
Serious — Power derate likely — plan to stop soon.
The most common cause is: Failed injector solenoid. Other possibilities include Broken wiring; corroded connector.
Power derate likely — plan to stop soon. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Related codes
Codes that commonly appear alongside P0203, or share the same subsystem.
- Injector Metering Rail 1 Pressure - Data Valid But Below Normal Operating Range (XPI common rail fuel pressure too low) (SPN 157 FMI 1)
- Fuel Delivery Pressure — Low (SPN 94 FMI 1)
- Injection Rail Pressure — Below Normal (SPN 157 FMI 18)
- Injector Metering Rail 1 Pressure - Data Valid But Above Normal Operating Range (XPI common rail fuel pressure too high) (SPN 157 FMI 0)
- Injector #1 open circuit (SPN 651 FMI 5)
- Injector #2 open circuit (SPN 652 FMI 5)
- Injector #3 open circuit (SPN 653 FMI 5)
- Injector #4 open circuit (SPN 654 FMI 5)
Same symptom: Fuel delivery
Other codes on the tank-to-injector path — pressure, filters, water and the pump.
- Fuel System Leak Detected - Large Leak (P0093) · Fuel System
- HP Fuel Rail Pressure Low During Power Enrichment (P1093) · Fuel System
- High-Pressure Fuel System Relief Valve Open (P2BAD) · Fuel System
- Injector #5 open circuit (SPN 655 FMI 5) · Fuel System
- Injector #6 open circuit (SPN 656 FMI 5) · Fuel System
- Fuel Rail/System Pressure Too Low (P0087) · Fuel System
Find a mechanic or related guides
General diagnostic guidance for diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack and more). Not a substitute for a scan-tool diagnosis on your specific truck.