OBD-II Code P0261 — What It Means & How to Fix It

What Does This Error Mean?

P0261 means the electrical signal controlling the fuel injector on Cylinder 1 is too low. The engine computer tried to fire the injector but received a lower-than-expected voltage reading back. This usually means a broken wire, bad connector, or failed injector coil on Cylinder 1. You'll likely feel the engine misfiring or running rough, especially at idle. Cylinder 1 may not be firing at all — which wastes fuel and can damage the catalytic converter.

Affected Models

All vehicles 1996+
Common in Ford, Chevrolet, Toyota, Honda
Common in direct injection engines
Common in vehicles with high mileage injector wiring
Seen frequently after engine work involving injector removal

Common Causes

Open circuit or broken wire in the cylinder 1 injector control wiring
Corroded or loose connector at the cylinder 1 fuel injector
Fuel injector internal coil has failed open (no electrical continuity)
Ground circuit fault causing low voltage return at the injector
ECM injector driver circuit failure on the cylinder 1 output

How to Fix It

Scan for all codes. P0261 alongside P0301 (cylinder 1 misfire) confirms that cylinder 1 is truly misfiring due to the injector issue. Just P0261 alone may mean the circuit fault hasn't completely disabled the injector yet.

A misfire code confirming alongside P0261 means you should act fast — a misfiring cylinder can damage your catalytic converter.
Inspect the cylinder 1 injector connector and wiring. Disconnect the connector and check for corrosion, bent pins, or pulled-back wires. Low-voltage codes often come from high resistance in the circuit.

Even slight corrosion increases circuit resistance enough to register as a low-signal fault.
Measure the resistance of the cylinder 1 injector using a multimeter across its two terminals. Compare to spec. An open reading (infinite resistance) means the injector coil has failed internally.

Most fuel injectors read 12–17 ohms when healthy. Higher resistance or open circuit = bad injector.
Check the voltage supply and ground at the injector connector while cranking. The injector needs a consistent power supply and a clean ground. A bad ground is a commonly missed cause of low-circuit codes.

A poor engine ground strap causes all kinds of mysterious electrical codes — inspect and clean all engine grounds.
If the injector measures bad, replace it. Use an OEM or quality aftermarket injector. If the injector tests good and wiring is clean, the ECM driver circuit for cylinder 1 may be at fault — have a shop test the ECM.

Before buying a new ECM, get a second opinion — ECM failures are often misdiagnosed.

When to Call a Professional

If wiring and connector checks look fine and the injector tests out of spec, replace the injector. If the fault follows the wiring and not the injector, you may have an ECM driver failure. ECM diagnosis and repair requires specialized equipment — bring it to a reputable shop. Expect $150–$400 per injector installed; ECM repairs can run $300–$1,500.

Frequently Asked Questions

Is P0261 a serious code?

Yes. A low injector circuit means cylinder 1 may not be firing properly. Misfiring cylinders send raw fuel into the exhaust, which overheats and can destroy the catalytic converter. A ruined catalytic converter costs $500–$2,000+ to replace. Fix P0261 before it creates a far more expensive problem.

Can I drive with P0261?

Short trips are generally okay, but extended driving is not recommended. If the check engine light is flashing (not just solid), that means active misfires — pull over and don't drive until it's fixed. A solid check engine light with P0261 gives you a little more time, but still don't delay.

How much does it cost to fix P0261?

Connector repair or cleaning: $50–$150. Wiring repair: $100–$350. Fuel injector replacement (single): $150–$400 installed. Ground strap repair: $50–$150. ECM repair (rare worst case): $300–$1,500.