P0208 — Injector Circuit/Open - Cylinder 8 — LB7 Duramax
Diagnostic reference for LB7 Duramax (2001–2004) P0208.
What it means
The ECM has detected an electrical fault in the cylinder 8 injector circuit. On the LB7 the injectors sit under the valve covers and are a well-known weak point.1
Most likely causes
- Injector harness or connector fault under the valve cover on cylinder 8 — Inspect the under-valve-cover injector harness and connector for chafing, oil intrusion, or terminal fretting. The LB7 injectors sit under the valve covers and are a well-known weak point; check the injector harness and connector under the valve cover, then the injector.1
- Faulty cylinder 8 injector (open coil or internal failure) — A failed injector can present as an open circuit.1
- ECM driver or wiring fault to cylinder 8 injector — Wiring damage or ECM driver issue can cause an open detection on the cylinder 8 injector circuit.1
How to diagnose
- Verify code P0208 is present and check for accompanying misfire or fuel-system codes.
- Inspect the under-valve-cover injector harness and connector for cylinder 8 for oil, chafing, or corrosion.
- Perform a resistance/continuity check of the cylinder 8 injector circuit from the ECM connector to the injector connector, looking for open or high resistance.
- Compare cylinder 8 injector electrical values to adjacent cylinders to isolate an injector vs. harness issue.
Specs and test values
| Check | Normal reading | When to measure | Source |
|---|---|---|---|
| Injector balance rates | Healthy engines sit near ±2 mm³; values near ±4 mm³ or one cylinder far from the rest need a closer look | Hot idle in Park, A/C off | BD Diesel |
Common mistake to avoid
Buying injectors on balance rates alone. Compression, rail pressure and the pressure regulator all move balance rates; confirm a suspect injector with a return-flow test before replacing it. Source: BD Diesel — LB7 injectors: balance rates and return tests.
Parts and tools you may need
- Digital multimeter
- Wiring diagram for LB7 injector circuits
- Valve cover gasket set (if cover removal required)
- Injector harness/connector repair kit
Tools you’ll need
- OBD-II scan tool — Confirms P0208 is active and reveals related misfire or fuel-system codes for cylinder 8.
- Digital multimeter — Measures resistance and continuity of the cylinder 8 injector circuit from ECM to injector to find opens or high resistance.
- Inspection mirror — Lets you view the under-valve-cover injector harness and connector on cylinder 8 for oil, chafing, or corrosion without full disassembly.
- Terminal release tool set — Safely disconnects and inspects the cylinder 8 injector connector pins for corrosion or damage under the valve cover.
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) | $250–$450 | 2–4 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
High-pressure fuel systems are hazardous. If diagnosis points to internal injector failure or ECM driver fault, have a qualified diesel technician confirm with proper test equipment before servicing high-pressure components.
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
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