P0277 code: Cylinder 6 Injector Circuit High
P0277 means cylinder 6 Injector Circuit High. The code says where to look, not what failed — the fix depends on which cause your car actually has.
What P0277 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.
P0277 symptoms
- 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 P0277
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 →
How to fix P0277
Moderate — doable at home with common tools and patience
- Think back to recent work on the engine
Rear-cylinder circuit codes commonly show up after a spark plug change, intake gasket job or valve-cover reseal. Check that the injector 6 connector is fully latched, that plugs weren't swapped between cylinders, and that the harness isn't trapped under the plenum or a bracket — a half-seated connector is an easy cause to overlook.
- Measure feed and control at the cylinder 6 plug
Key on with injector 6 unplugged: confirm battery voltage on the feed terminal, then check the control terminal. Battery voltage there means the control wire is touching a powered circuit; nothing at all is normal on some systems and a small reference voltage on others, so compare with a known-good cylinder's connector.
- Check injector 6 for an open coil
Read resistance across the injector terminals and compare with the other injectors on the engine; around 11–18 ohms is typical for high-impedance port injectors. An open circuit or a markedly higher value means injector 6 is finished, while a matching value sends you back to the wiring.
- Flex-test the harness at the back of the engine
Engine rock flexes the harness most where it leaves the main loom near the firewall. With an ohmmeter across the injector 6 control wire from module to connector (battery and module disconnected), work along that section by hand; a reading that jumps or goes open marks the fatigued spot.
- Repair, reroute and recheck
Fix the wire or connector, or replace injector 6, then route the harness exactly as original with every clip in place. Clear codes and drive a full warm-up cycle; if P0277 returns with injector and wiring proven good, a shop should check the module driver with a scope before anything else is replaced.
DIY or shop? Latching a connector, checking voltages and reading resistance are all comfortable home tasks, and after recent engine work they often solve it outright. Reaching the cylinder 6 injector is the dividing line: an accessible inline-six rail is moderate DIY, but a rear-bank V6 injector under the plenum, or any direct-injection engine where the drivers run boosted voltage and the injectors need special seals, is better left to a shop.
Tools for the DIY steps: Digital multimeter · Back-probe pins · Flashlight and inspection mirror · Socket set and extensions · Harness clips and zip ties
Not sure which step applies to your car? Get the likely cause for your exact vehicle before buying anything for P0277.
Start a case with P0277 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 P0277?
Redline can’t determine from a symptom or code alone whether your car is safe to drive.
P0277: common questions
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?
It could well be. 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?
A code alone can't settle that. 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, and if the check-engine light flashes or the engine shakes heavily, stop driving.
Related trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0277 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 P0277 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.