P0203 — Injector Circuit Open Cylinder 3
Seen on: Heavy Truck/Diesel
Injector Circuit Open Cylinder 3. Common causes: Failed injector solenoid.
Your code rides along, so nearby mechanics see the fault before they quote you.
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.
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.