P0261 code: Cylinder 1 Injector Circuit Low
P0261 means cylinder 1 Injector Circuit Low. The code says where to look, not what failed — the fix depends on which cause your car actually has.
What P0261 means
Each fuel injector is an electrically operated valve, and the engine computer (ECM) watches the voltage on every injector's control circuit as it fires. P0261 sets when the circuit for the cylinder 1 injector reads lower than expected — classic signs of a wire shorted to ground, an open circuit, or an injector coil that has failed internally. This is an electrical fault, which makes it different from a mechanically clogged injector: a clogged injector usually sets a misfire code, not a circuit code. Because the fault is specific to cylinder 1, comparing that injector and its wiring to a healthy neighboring cylinder is the fastest way to diagnose it. You will often see it alongside P0201 (cylinder 1 injector circuit) or P0301 (cylinder 1 misfire), since a dead injector circuit means a dead cylinder. Note that which cylinder is 'number 1' depends on your engine's layout, so check the firing-order diagram for your specific engine before pulling parts.
P0261 symptoms
- Misfire or rough running traced to cylinder 1
- Rough idle and possible shaking at a stop
- Reduced power, especially under load
- Check-engine light, which may flash if the misfire is active
- Sometimes no symptoms at all if the fault is intermittent
What it costs to fix P0261
Typical range: $60–$450 · about ~0.5–2 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Fuel injector (single) | $50–$300 | ~0.5–2 hrs |
| Wiring/connector repair | $5–$50 | ~0.5–2 hrs |
A wiring or connector repair is cheap once found; the injector itself is the bigger-ticket item. On V-type engines where the intake manifold has to come off to reach the injector, and on direct-injection engines whose injectors cost more and sit under high fuel pressure, expect the high end.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0261 for my exact vehicle →
How to fix P0261
Moderate — doable at home with common tools and patience
- Map out cylinder 1 and note every stored code
Use a numbering diagram for your engine — on most inline engines cylinder 1 sits at the timing-belt or chain end, but V layouts vary. Then list everything stored: a lone P0261 (perhaps with P0201 or P0301) points at this one injector or its wire, while low codes on several injectors at once suggest a shared feed, ground or module problem.
- Plug a noid light into the injector 1 connector
Unplug injector 1 and fit the matching noid light. While cranking it should blink; a lamp that stays lit the whole time means the control wire is pulled to ground continuously, which can also hold the injector open and wash the cylinder with fuel. A normal blink shifts suspicion to the injector itself. Skip this on direct-injection engines and use the service manual's procedure.
- Ohm injector 1 against the others
With the connector off, measure across the injector's two terminals and repeat on two or three other cylinders. High-impedance injectors commonly read somewhere around 11–18 ohms, but the comparison matters more than the number: injector 1 reading clearly lower than its neighbours is the shorted-winding signature behind many circuit-low codes.
- Test the control wire for a short to ground
Disconnect the battery, unplug the ECM connector and injector 1, then measure from the control wire to a clean engine ground. It should read open; any continuity means insulation has worn through, so follow the harness from the timing end along the fuel rail and over brackets until the reading changes as you move it.
- Replace the injector before suspecting the ECM
If the winding tested short, relieve fuel pressure and replace injector 1 with new O-rings, then clear codes and recheck. Only blame the ECM's driver once both injector and wire test good — and never fit a replacement module with a shorted injector still connected, since the same fault can damage the new driver.
DIY or shop? Everything up to the injector swap is driveway work with a meter and a noid light, and cylinder 1 is usually one of the easier injectors to reach on inline engines. Replacing a port injector means relieving fuel pressure and lifting the rail, which is manageable with care and new seals. It turns into shop work when the short is buried inside a taped harness under the intake, when the engine is direct-injected (high fuel pressure and high-voltage drivers), or when the ECM needs replacing and programming.
Tools for the DIY steps: Digital multimeter · Noid light set · OBD-II scan tool · Socket set for the fuel rail · Injector O-ring kit
Not sure which step applies to your car? Get the likely cause for your exact vehicle before buying anything for P0261.
Start a case with P0261 and your car. Redline weighs these causes against what your car shows, and names the check that would settle it before you buy parts.
Can I drive with P0261?
Redline can’t determine from a symptom or code alone whether your car is safe to drive.
P0261: common questions
What does 'circuit low' mean on P0261?
The ECM saw lower voltage than expected on the cylinder 1 injector's control circuit. That points to a short to ground, a broken wire, or an injector coil that has failed electrically — an electrical problem, not a dirty or clogged injector.
Is P0261 the injector or the wiring?
Either. Measuring the injector's resistance and comparing it to the other cylinders is the quickest sort: if it matches the others, suspect the harness and connector; if it reads shorted or open, the injector itself is the likely culprit. Swapping it with a neighbor and seeing if the code follows also settles it.
Can I keep driving with P0261?
A code alone can't settle that. A dead or erratic cylinder pushes raw fuel at the catalytic converter, and a flashing light means that damage risk is active — stop driving. Treat this as a fix-soon code, not one to ignore for months.
How is P0261 different from P0301?
P0301 says cylinder 1 is misfiring but doesn't say why; P0261 says the electrical circuit to cylinder 1's injector is faulty. When both appear together, the circuit fault is almost certainly causing the misfire, so chase the electrical problem first.
Related trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0261 from your phone. See our guide to the best OBD2 Bluetooth adapters. Run a repair shop? See Redline for shops.
Generic OBD-II reference. Manufacturer-specific behavior varies. Confirm with a scan tool and, for safety-related codes, a professional inspection. Cost ranges are reference ranges, not quotes.
Seeing P0261 on your car?
Every problem becomes a Case. Tell Redline what the car is doing: it shows what the evidence supports, what’s still missing, and what to check next, before you approve a repair.
“Inner pad ~1 mm. Outer pad 3 mm.”
Next: check the slide pins move freely before buying parts.