P0206 — Injector Circuit/Open - Cylinder 6 — 5.9 Cummins Common Rail
Diagnostic reference for P0206 on 5.9L Cummins Common Rail 2003-2007.
What it means
The ECM has detected an electrical fault in the fuel injector circuit for cylinder number six. On the 5.9L Cummins Common Rail 2003-2007 ISB, injectors are Bosch common-rail solenoid type and electrical faults show as P0201-P0206; contribution/balance faults are P0263-family. This platform uses a CP3 pump with FCA/MPROP and rail pressure sensor/relief valve, has no EGR/DPF/SCR/DEF, no VGT, grid heater not glow plugs.12345
Most likely causes
- Open or high resistance in cylinder 6 injector wiring/connector — Inspect the injector harness and connector at cylinder 6 for chafing, oil intrusion, corrosion, or loose terminals. Check continuity and isolation of the injector control circuit from ECM to injector. Compare resistance to adjacent cylinders.12345
- Failed or internally open Bosch common-rail solenoid injector on cylinder 6 — A solenoid injector with an open coil will set P0206. Electrical check of injector resistance at the connector versus spec and comparison to other cylinders helps isolate an injector fault from wiring.12345
- ECM driver fault for cylinder 6 injector circuit — If wiring and injector test good, the ECM internal driver for cylinder 6 may be faulty. Verify power/ground and reference signals to ECM and inspect for water intrusion before condemning ECM.12345
- Chafed engine harness near valve cover / injector rail — The injector harness runs close to hot/valve-cover areas and can chafe. Look for rubbed-through insulation causing intermittent open/short, especially on cylinder 6.12345
How to diagnose
- Verify code and freeze frame; confirm P0206 is present and not accompanied by rail pressure or contribution codes.
- Visually inspect cylinder 6 injector connector and harness for damage, oil, corrosion, or loose pins.
- Measure injector solenoid resistance at cylinder 6 connector and compare to cylinders 1-5; look for open/infinite resistance.
- Check continuity and isolation of injector control circuit from ECM connector to cylinder 6 injector connector; inspect for chafing along harness route.
- Inspect ECM connectors for corrosion/moisture; verify ECM power and ground circuits.
- Clear codes, run engine and monitor for P0206 reset; if code returns with good wiring and injector resistance, suspect ECM driver.
- Note: contribution/balance faults are P0263-family; P0206 is electrical circuit/open, not a performance/balance issue.
Parts and tools you may need
- Digital multimeter
- Wiring diagram for 2003-2007 5.9L Cummins Common Rail
- Injector breakout harness or back-probe pins
- Dielectric grease
- Trim removal tools
Tools you’ll need
- digital multimeter — Measures injector solenoid resistance and wiring continuity to confirm an open or high-resistance fault on cylinder 6.
- OBD-II scan tool — Reads and clears P0206 and freeze frame to verify the electrical fault and monitor code reset after repairs.
- inspection mirror — Allows visual inspection of cylinder 6 injector connector and harness routing in the tight valve cover area for chafing or damage.
- terminal release tool set — Safely releases and reseats injector connector terminals to check for corrosion, loose pins, or poor contact without damage.
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 good but code persists, or ECM driver is suspected, have a qualified diesel technician perform ECM output tests and injector circuit verification. 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
Curated DTC seed — 5.9 Cummins Common Rail (curated) ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Curated DTC seed — 5.9 Cummins Common Rail (curated) ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Curated DTC seed — 5.9 Cummins Common Rail (curated) ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Curated DTC seed — 5.9 Cummins Common Rail (curated) ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Curated DTC seed — 5.9 Cummins Common Rail (curated) ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Repair videos: P0206 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.
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