P0205 on GMC
Injector Circuit/Open - Cylinder 5
P0205 on GMC vehicles indicates injector circuit/open - cylinder 5. Au7o has documented this code across 2 GMC models — most commonly on Sierra 2500HD, Sierra 3500HD. P0205 is a fuel-system code meaning the engine computer detected an electrical problem (an open circuit or out-of-range condition) in the fuel injector circuit for cylinder number 5. The PCM controls each injector with a precise electrical pulse, and it monitors that circuit for proper current flow. When the cylinder 5 injector circuit doesn't respond as expected — typically an open or a wiring fault — this code sets. It generally causes a misfire on that cylinder, rough idle, hesitation, reduced power, and possibly hard starting, since cylinder 5 isn't being fueled correctly. Typical repair costs on GMC range from $600 to $6,500, depending on the specific model and root cause.
Common Causes of P0205
- •Failed or open fuel injector on cylinder 5
- •Open or shorted wiring in the injector control circuit
- •Corroded, loose, or damaged injector connector
- •Poor power feed or driver fault from the PCM/injector circuit
- •Chafed or broken injector harness
- •Blown fuse feeding the injector bank (where applicable)
- •PCM injector driver failure (less common)
P0205 on GMC by Model
GMC Sierra 2500HD(1 issue)
- LB7 Duramax Injector Body Cracking and Ball-Seat Erosion Causing Fuel-in-Oil Dilution2001-2004
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.
GMC Sierra 3500HD(1 issue)
- Diesel Injector Failure Causing White Smoke and Rough Running2015-2024
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.
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View P0205 across all makes →Frequently Asked Questions
What does P0205 mean on GMC?▼
P0205 stands for "Injector Circuit/Open - Cylinder 5." P0205 is a fuel-system code meaning the engine computer detected an electrical problem (an open circuit or out-of-range condition) in the fuel injector circuit for cylinder number 5. The PCM controls each injector with a precise electrical pulse, and it monitors that circuit for proper current flow. When the cylinder 5 injector circuit doesn't respond as expected — typically an open or a wiring fault — this code sets. It generally causes a misfire on that cylinder, rough idle, hesitation, reduced power, and possibly hard starting, since cylinder 5 isn't being fueled correctly. On GMC specifically, this code is documented across 2 models.
What causes P0205 on GMC vehicles?▼
Common causes on GMC: Failed or open fuel injector on cylinder 5, Open or shorted wiring in the injector control circuit, Corroded, loose, or damaged injector connector, Poor power feed or driver fault from the PCM/injector circuit, Chafed or broken injector harness. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0205 on a GMC?▼
Repair costs on GMC range from $600 to $6,500, depending on the specific model and root cause.
Which GMC models have P0205 documented?▼
Au7o has documented P0205 on 2 GMC models: Sierra 2500HD, Sierra 3500HD.