OBD codes / P0261
P0261
ModerateCylinder 1 Injector Circuit Low
A cylinder 1 injector circuit fault usually means that cylinder is dead or firing erratically, which sends unburned fuel into the exhaust and can overheat the catalytic converter. Short, gentle drives are usually tolerable, but if the check-engine light flashes, ease off and get it diagnosed right away rather than continuing to drive.
What this code 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.
Symptoms you might notice
- 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
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 →
Frequently asked
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?
Briefly, if the engine runs acceptably and the light is steady. But a dead or erratic cylinder pushes raw fuel at the catalytic converter, and a flashing light means that damage risk is active — so 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.
Seeing P0261 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0261 for my vehicleRelated trouble codes
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Generic OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.