P0261 on 2003-2007 Ford F-350 — Cylinder 1 Injector Circuit Low
1 vehicles · 1 makes · $350-$1,100 repair
How to diagnose and fix P0261: most-reported vehicles
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Ford F-350 · 2003–2007
The 6.0L Power Stroke's Fuel Injection Control Module sits on top of the driver-side valve cover and must deliver a 48-volt pulse to fire each HEUI injector. The module is heat-soaked in that location and its internal power supply degrades over time; it is also killed outright by weak batteries or a failing charging system, because the boost circuit is damaged when supply voltage sags during cranking. As FICM main power output drops below roughly 46 volts, the injector solenoids begin to open late, producing hard starting, rough cold running and white smoke. A dying FICM can subsequently damage injectors. F-350s with two batteries that are not replaced as a matched pair are the classic case.
Common Symptoms
- Extended cranking / hard start, worse when cold
- Rough idle and misfire for the first minutes after start
- White smoke at startup
- No-start with normal cranking speed
- FICM main power below 45 volts on a scan tool
- Repeat injector failures
How to Fix
Read FICM main/logic/vehicle power with a scan tool (IDS or a capable aftermarket tool) at key-on and while cranking. Main power should read about 48 volts; anything below 45 volts, even momentarily, indicates a failing module. Fix the batteries and charging system FIRST, then have the FICM rebuilt with upgraded power-supply components (common, and far cheaper than a new module) or install a remanufactured unit. No recall covers this. Replacing the FICM without correcting weak batteries will kill the new module too.
Sources for this issue (4)
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P0261 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 P0261 mean?
P0261 stands for "Cylinder 1 Injector Circuit Low." The PCM detected low voltage (short to ground or open on the power side) in the cylinder 1 fuel injector control circuit. The injector cannot be properly energized, leading to a misfire on that cylinder.
What are the most common causes of P0261?
The most common causes of P0261 are: Short to ground in cylinder 1 injector wiring, Open on the injector power feed, Faulty cylinder 1 injector, Loose or corroded connector, PCM injector driver fault. The specific cause varies by vehicle.
How much does it cost to fix P0261?
Repair costs for P0261 range from $350 to $1,100, depending on the vehicle and root cause.
Which vehicles are affected by P0261?
Au7o has documented P0261 across 1 vehicle models from 1 manufacturers: Ford.
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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.