P0208: How to Diagnose & Fix — Injector Circuit/Open - Cylinder 8
4 vehicles · 3 makes · $100-$6,500 repair
How to diagnose and fix P0208: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Chevrolet Silverado 2500HD · 2001–2016
The fuel injector wiring harness on the Duramax diesel routes across the top of the engine under the valve covers. The harness rubs against the valve cover and rocker arms, causing the insulation to wear through and the wires to short or open. When an injector wire is damaged, the affected cylinder misfires, the engine runs rough, and white smoke pours from the exhaust. The chafing is accelerated by engine vibration and can affect multiple cylinders over time. GM released updated harness routing clips but the fundamental design has the harness in a high-wear location.
Common Symptoms
- Engine misfires on one or more cylinders
- White smoke from exhaust
- Rough idle that develops gradually
- Check engine light with injector circuit codes
- Engine runs on fewer than 8 cylinders
- Intermittent misfires that come and go
How to Fix
Remove the valve covers and inspect the injector harness for chafing (requires 2-3 hours labor). Damaged sections can be repaired with heat-shrink tubing and solder ($100-$300 for repair). If the harness is severely damaged in multiple places, a complete replacement harness costs $200-$500 and takes 3-5 hours to install. Add additional harness routing clips and protective loom to prevent recurrence. Some diesel specialists reroute the harness outside the valve cover (external harness conversion) to eliminate the chafing issue permanently.
Sources for this issue (1)
Ford F-250 · 1990–1998
The 7.3L diesel engines (IDI pre-1994, Powerstroke 1994+) experience injector failure causing rough running, hard starts, and excessive smoke. The IDI injectors are simpler mechanical units; Powerstroke uses HEUI hydraulic electronic injectors.
Common Symptoms
- Hard starting
- Black or white smoke
- Rough idle
- Knocking noise
- Loss of power
How to Fix
Sources for this issue (1)
GMC Sierra 3500HD · 2015–2024
The Bosch piezoelectric fuel injectors on the Duramax L5P and LML engines can fail due to contaminated fuel, high-mileage wear, or internal electrical faults. A failed injector causes white smoke on startup, rough idle, misfires on the affected cylinder, and fuel dilution of the engine oil. The high fuel rail pressures (up to 36,000 PSI on the L5P) stress the injectors over time. Contaminated fuel from bulk diesel stations accelerates injector wear.
Common Symptoms
- White or gray smoke on cold start
- Rough idle or misfire on one or more cylinders
- Fuel smell in engine oil (fuel dilution)
- Check engine light with injector circuit codes
- Reduced power and poor fuel economy
- Hard starting in cold weather
How to Fix
Diagnose the failed injector with a relative compression test and injector balance rate scan using a Tech 2 or equivalent scan tool. Replace the failed injector(s) — OEM Bosch injectors are $300-$500 each, and labor is 2-4 hours per injector ($300-$600). Always replace the injector hold-down clamp and fuel return line seals. If one injector fails at high mileage, consider replacing all 8 as the others are likely near end of life. Use a quality fuel additive like Stanadyne or Hot Shot Secret to protect remaining injectors.
Sources for this issue (1)
GMC Sierra 2500HD · 2001–2004
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P0208 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0208 mean?
P0208 stands for "Injector Circuit/Open - Cylinder 8." This code means the engine computer detected an open or out-of-range condition in the fuel injector circuit for cylinder 8. Fuel injectors are electrically operated valves, and the computer continuously checks that each one's circuit responds correctly when commanded to open. When cylinder 8's injector circuit reads as broken, shorted, or electrically abnormal, this code sets — frequently accompanied by a misfire or rough running on that cylinder. The fault is electrical (wiring, connector, or the injector itself), not a fuel-supply issue.
What are the most common causes of P0208?
The most common causes of P0208 are: Corroded, loose, or damaged injector connector at cylinder 8, Open, shorted, or chafed wiring in the injector circuit, Failed fuel injector (open internal winding), Poor ground or power feed to the injector driver, Failed injector driver circuit inside the ECM/PCM, Water intrusion or pin corrosion in the engine harness. The specific cause varies by vehicle.
How much does it cost to fix P0208?
Repair costs for P0208 range from $100 to $6,500, depending on the vehicle and root cause.
Which vehicles are affected by P0208?
Au7o has documented P0208 across 4 vehicle models from 3 manufacturers: Chevrolet, Ford, GMC.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.