OBD codes / P0277
P0277
ModerateCylinder 6 Injector Circuit High
Cylinder 6 dropping out means unburned fuel in the exhaust and a catalytic converter running hotter than designed. Treat this as a prompt repair — light use is usually okay in the short term, but a flashing check-engine light or heavy shaking means stop driving.
What this code means
When the voltage on the cylinder 6 injector control circuit rises above the window the ECM expects, P0277 sets. High-side faults come from two directions: a short to battery voltage somewhere in the harness, or unwanted resistance from a corroded connector, damaged terminal, or an injector winding that has failed open. Fuel deposits and clogged nozzles are a different failure mode entirely — they starve the cylinder mechanically without disturbing circuit voltage, so this code genuinely points at the electrical side. Since only cylinder 6 is flagged, benchmarking against a healthy cylinder is fast, and swapping injectors between cylinders shows definitively whether the part or the wiring is to blame. P0206 and P0306 are the companion circuit and misfire codes for this cylinder. Remember that cylinder 6's location depends on the engine — inline versus V layouts number cylinders differently — so check your engine's diagram.
Symptoms you might notice
- Misfire or dropout on cylinder 6
- Rough idle, vibration, and uneven running
- Hesitation and reduced power under acceleration
- Check-engine light, flashing if the misfire is active
- May be stored with no symptoms when 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 cleaned connector or spliced wire keeps this cheap. Injector replacement raises the bill, and access matters: V-engine injectors under the intake manifold and high-pressure direct-injection injectors both add parts cost and labor.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0277 for my exact vehicle →
Frequently asked
What causes an injector circuit to read high?
Either the circuit is contacting battery voltage through a chafed or shorted wire, or something has added resistance — corroded connector pins, a damaged terminal, or an injector coil that has failed open. Both push the voltage signature above what the ECM expects for cylinder 6.
Should I check the wiring before buying an injector?
Yes. Connector corrosion and harness damage cause a large share of circuit-high codes and cost almost nothing to fix. Unplug the cylinder 6 connector, inspect the pins, and measure the injector's resistance — only a shorted or open reading justifies a new injector.
Can P0277 be intermittent?
Very commonly. A marginal connection can conduct fine when cold and fail when heat expands the metal or vibration jostles the pins, so the code sets, clears, and returns. That pattern strongly suggests a connector or harness fault rather than a cleanly failed injector.
Is it safe to drive with P0277?
For short, gentle trips with a steady light, generally yes. The real hazard is cumulative: continued misfire from cylinder 6 can overheat and ruin the catalytic converter, which turns a modest electrical repair into an expensive exhaust job. Fix it promptly.
Seeing P0277 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0277 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.