What does 'circuit high' actually mean on an injector?

It means the ECM measured more voltage on the injector control wire than it should see when it commands the injector to fire. The module fires an injector by pulling that wire to ground, so the voltage should drop during each pulse. If it stays up, either nothing is connected for the ground pull to act on (an open circuit) or something else is actively feeding the wire with power (a short to voltage).

I have high codes on several injectors at once. Where do I start?

With the shared power feed, not with the injectors. On six- and eight-cylinder engines the injectors are fed in groups, often one group per bank, through a common fuse and relay. Lose that feed and every injector in the group reports abnormally. Check for battery voltage at two or three injector connectors on the affected bank with the key on. If it is absent at all of them, the fault is the fuse, the relay, or the feed wire — one repair fixes every code.

Is P0274 safe to drive with?

It is best avoided. Cylinder 5 is effectively dead, so the engine is down on power and pushing unburned fuel and air into the exhaust, which can overheat and destroy the catalytic converter serving that bank. Drive gently and directly to a shop, and if the check engine light is flashing, pull over and have the vehicle towed.

How is P0274 different from P0205?

Both point at the cylinder 5 injector circuit, but they describe the fault differently. P0205 is the generic 'Injector Circuit/Open' code — the ECM reports the circuit is not complete. P0274 is a voltage-level report: the control wire measured high when the module commanded it low, which is caused by an open circuit or by a short to power. Many vehicles will set one or the other depending on how the manufacturer implemented the monitor, and on some you will see both stored together. The diagnostic path is largely the same, with the added step on P0274 of checking the control wire for unexpected voltage.

OBD-II trouble code

P0274: Cylinder 5 Injector Circuit High

The cylinder 5 injector control circuit read higher than expected — normally an open circuit or a short to battery voltage. If other injectors on the same bank also set codes, check the shared power feed first.

Medium severityPowertrainFuel InjectorsDo not drive

Quick facts

System: Powertrain
Category: Fuel Injectors
Severity: Medium severity
Drivable: No — stop driving until repaired
Repair cost range: $30 – $1,500
DIY difficulty: Intermediate DIY

What does P0274 mean?

P0274 is the opposite condition from P0273 on the same circuit. The engine control module (ECM) fires the cylinder 5 injector by pulling its control wire to ground, and it monitors that wire to confirm the voltage actually drops when a pulse is commanded. P0274 sets when the voltage stays high — the ECM tried to pull the circuit down and the circuit did not follow.

Only two conditions produce that result. The first is an open circuit: a broken wire, a disconnected or corroded connector, or an injector with a broken coil winding means the ECM's ground path connects to nothing, so the voltage never drops. The second is a short to battery voltage, where some other power source is feeding the control wire and holding it up against the module. Both look identical from inside the ECM, and separating them is the first genuinely useful step.

That short list of suspects is the practical advantage of a high code over a low one. A low code can arise from three different faults that all read the same on a scan tool; a high code narrows to open-versus-shorted-to-power, and a continuity check across the injector plus a voltage check on the control wire with the ECM unplugged usually settles it inside half an hour.

One thing to check early on any six- or eight-cylinder engine: injectors are almost never fed power individually. They are grouped, frequently by bank, through a common fuse and relay or through a single feed wire that splices out to each injector on that side. If the feed to cylinder 5's group is lost, the ECM's control-side measurement goes abnormal and can set a high code on several injectors at once — and no injector replacement will fix any of them. If P0274 has arrived together with high codes on other cylinders that share its bank, treat the shared feed as the prime suspect rather than testing each injector in turn.

With the circuit stuck high, cylinder 5 receives little or no fuel, so a misfire is essentially guaranteed and P0305 commonly appears with it. Unburned fuel and air passing into the exhaust can overheat and ruin the catalytic converter on that bank, so this is not a code to defer.

Common causes

Open circuit in the cylinder 5 injector control wire (broken conductor or corroded splice)
Open coil winding inside the cylinder 5 injector
Injector connector unplugged, unlatched, or with a spread or corroded terminal
Loss of the switched power feed shared by the injectors on that bank — a blown fuse or a failed relay
Control wire shorted to battery voltage or to another powered circuit
Chafed harness contacting a powered wire, stud, or terminal
Connector left unseated after intake manifold or valve cover service
Rarely, a failed cylinder 5 injector driver inside the ECM/PCM

Symptoms

Check engine light on, sometimes flashing under load
Dead or very weak cylinder 5 with a rough, shaking idle
Misfire codes such as P0305 or P0300 stored alongside
Marked loss of power and hesitation
Raw fuel odor from the exhaust
Poor fuel economy
Hard starting or extended cranking

Diagnostic steps

1.Confirm P0274 and record every companion code. High codes on multiple cylinders of the same bank point at a shared power feed, not at the injectors.
2.Identify cylinder 5 for your specific engine in the service information — the numbering varies significantly between manufacturers on V6 and V8 engines.
3.Inspect and fully reseat the cylinder 5 injector connector. A connector left unlatched after prior service or a pin that has backed out is a common and free fix.
4.Unplug the injector with the key off and measure its coil resistance. An infinite or very high reading confirms an open winding and condemns the injector.
5.With the key on and the injector unplugged, confirm battery voltage is present on the feed side of the connector. If it is missing, the fault is upstream — a fuse, a relay, or the feed wire — and replacing the injector will accomplish nothing.
6.Disconnect both the injector and the ECM connector and check the control wire end to end for continuity. No continuity confirms an open in the harness.
7.With the ECM connector still disconnected, check the control wire for unexpected voltage. Voltage present there means the wire is shorted to a power source that must be located and repaired.
8.Once the wiring and injector both test correct, use a noid light or a scan tool injector test to verify the ECM is actually pulsing the circuit before considering the module.

Repair cost

$30 – $1,500

A blown fuse or failed injector relay is often under $100, and a simple unlatched connector costs nothing but time. Repairing a broken wire or a corroded terminal typically runs $75-$250. A single gasoline fuel injector is $60-$400 in parts plus 0.5-3 hours labor depending on access; a cylinder 5 injector under a V6 or V8 intake manifold sits at the upper end, and diesel injectors commonly reach $400-$900 installed. A failed ECM injector driver is uncommon and runs $500-$1,500 including programming. Diagnosis alone is typically $75-$150.

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DIY vs shop

This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.