P0201 — Injector Circuit/Open - Cylinder 1 — 5.9 Cummins Common Rail
Diagnostic reference for P0201 on 5.9 Cummins Common Rail 2003-2007.
What it means
The engine control module has detected an electrical fault in the fuel injector circuit for cylinder number one. On this platform the 5.9L Cummins Common Rail 2003-2007 ISB uses Bosch common-rail solenoid injectors; electrical faults show as P0201-P0206; contribution/balance issues show as P0263-family.12
Most likely causes
- Open or high resistance in injector 1 wiring/harness or connector — Chafing, heat damage, or corrosion at the injector 1 connector or engine harness can create an open circuit detected by the ECM.12
- Faulty injector 1 solenoid/coil — Internal open in the Bosch common-rail solenoid injector for cylinder 1 will set an electrical circuit fault.12
- ECM driver fault for injector 1 — Internal ECM injector driver failure or poor ECM connector/pin contact can appear as a circuit/open for cylinder 1.1
- Poor ground or power supply to injector rail — Shared power/ground issues affecting the injector group can trigger a single-cylinder circuit code.1
How to diagnose
- Verify code and freeze frame; confirm P0201 is present and not accompanied by rail pressure or contribution codes.
- Inspect injector 1 connector and engine harness for chafing, heat damage, oil contamination, and secure lock. Compare visually to other injectors.
- Check ECM and injector harness connectors for corrosion, bent pins, and proper seating.
- Perform electrical tests at the injector connector for continuity and isolation per service information; compare injector 1 readings to adjacent cylinders.
- Inspect related grounds and power feeds for the injector group.
- If electrical tests pass, evaluate injector 1 solenoid resistance/signature against spec and compare to other cylinders.
- Review recent work, heat exposure, or fluid leaks that could affect the injector 1 circuit.
- Clear codes and monitor for reoccurrence under normal driving conditions.
Parts and tools you may need
- Digital multimeter
- Scan tool with live data and code read/clear
- Inspection light
- Contact cleaner
- Dielectric grease
Tools you’ll need
- digital multimeter — Measures injector 1 solenoid resistance and wiring continuity to compare with adjacent cylinders and detect opens or high resistance.
- OBD-II scan tool — Confirms P0201 presence, reviews freeze frame data, and monitors code reoccurrence after repairs without contribution codes.
- inspection light — Reveals chafing, heat damage, oil contamination, and connector lock issues on injector 1 harness versus other injectors.
- terminal release tool set — Allows safe inspection and reseating of ECM and injector connector terminals for corrosion or bent pins.
Rough cost and difficulty
| Likely repair | Parts | Shop labor | Who usually does it |
|---|---|---|---|
| Wiring or connector repair | $10–$100 | 1–4 hrs | DIY with tools and a manual |
| Injector wiring harness / under-valve-cover harness | $50–$300 | 2–5 hrs | Shop |
| Fuel injector (each) | $300–$600 | 1–2 hrs | Shop |
| ECM/PCM replacement (programmed) | $600–$2,000 | 1–3 hrs | Shop |
Typical US independent-shop figures; labor runs about $120–$180 per hour (dealers charge more). Confirm the diagnosis before buying parts.
When to see a pro
If wiring tests are inconclusive, injector electrical values are out of spec, or ECM driver is suspected, have a qualified diesel technician perform pinpoint electrical tests and ECM evaluation. Do not attempt high-pressure fuel system service without proper training and tools.
Check for recalls
Recalls are tied to your truck’s VIN, so check yours directly: enter the VIN at NHTSA’s recall lookup. Open safety recalls are repaired free at a dealer.
Sources
Repair videos: P0201 on the 5.9 Cummins CR
Third-party videos, not ours — picked for this engine. Confirm anything against the factory service information for your truck.
Spotted an error, or something missing? Tell us
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