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.
Ford F-250 · 1990–1997
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 (2)
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
The 2001-2004 6.6L Duramax RPO LB7 uses injectors buried under the valve covers that are notorious for failing well before 150,000 miles. GM's own analysis attributed the failures to fuel injector body cracks, ball seat erosion, and high-pressure seal extrusion. A leaking injector dumps unburned diesel into the cylinder and past the rings into the crankcase, raising the oil level and diluting it. Owner reporting on duramaxforum.com and silveradosierra.com consistently puts first failures in the 100k-150k range, and because the injectors sit under the valve covers the labor to reach them is far higher than on the later LLY/LBZ engines, where injectors are accessible from the top. This is an LB7-only failure mode - the LLY and later injectors were redesigned and do not share it.
Common Symptoms
- White or blue smoke at idle once warmed up
- Strong raw fuel smell from the exhaust
- Engine oil level rising between changes and smelling of diesel
- Rough idle and misfire, especially cold
- Hard starting
- Knocking/rattle under load
How to Fix
Replace all eight injectors as a set (replacing one at a time invites repeat teardown labor), along with the injector return lines and valve cover gaskets. GM issued a Special Policy extending injector coverage to 7 years/200,000 miles for qualifying trucks after a dealer balance-rate test - that program has long expired, so repairs are now owner-paid. Reman Bosch or new injectors plus the required ECM injector-code programming is the correct repair; change the oil immediately afterward because of the fuel dilution.
Sources for this issue (3)
Chevrolet Silverado 2500HD · 2001–2016
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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.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.