P0280 code: Cylinder 7 Injector Circuit High
P0280 means cylinder 7 Injector Circuit High. The code says where to look, not what failed — the fix depends on which cause your car actually has.
What P0280 means
P0280 is the high-voltage counterpart to P0279: the ECM caught the cylinder 7 injector circuit reading above its expected range. That usually means the circuit is touching battery voltage through damaged insulation, or that resistance has crept in through a corroded connector, a failing terminal, or an injector winding that has gone open. Since this monitor tracks electrical behavior rather than fuel flow, it's a different problem from a clogged injector — no additive will help. You'll only see this code on engines with seven or more cylinders, primarily V8s and up, and the abundance of identical sibling circuits makes comparison testing easy. Watch for P0207 (circuit) and P0307 (misfire) stored with it. Because manufacturers number V-engine banks differently, verify cylinder 7's physical location on your engine before pulling connectors.
P0280 symptoms
- Cylinder 7 misfire — may feel like a light stumble on a V8
- Slightly rough idle and reduced smoothness
- Power loss under load or towing
- Check-engine light; flashing signals an active misfire
- Possible code storage with no symptoms if intermittent
What it costs to fix P0280
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 |
Connector and wiring repairs are inexpensive; the injector is the bigger cost. On V-engines the intake often has to come off to reach the injectors, and direct-injection injectors are pricier parts — both push toward the top of the range.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0280 for my exact vehicle →
How to fix P0280
Moderate — doable at home with common tools and patience
- Unplug and inspect the cylinder 7 connector
Release the latch on injector 7's plug and look into both halves for green corrosion, a pushed-back pin, or a broken lock tab. Then slide a matching test terminal into each harness socket — it should drag. A loose grip opens the circuit with vibration or heat, which is how a high-side code sets on the road but never in the driveway.
- Measure injector 7 cold, then again hot
Ohm the injector with the engine cold and again right after a full warm-up, comparing each reading with an injector on the other bank. A winding that reads in line cold but climbs far higher or shows OL once hot is opening up internally — exactly the kind of fault that sets P0280 on and off.
- Plug a noid light into the cylinder 7 harness
With the injector unplugged, fit the correct noid light to the harness connector and crank the engine. A steady flash proves the feed, the wiring, and the ECM driver are all working, which narrows it to the injector or its terminals; a dark light means checking the feed pin first, then the control wire back to the ECM.
- Hunt for battery voltage on the control wire
Disconnect the battery, unplug both the injector and the ECM connector, then reconnect the battery and switch the key on. The control wire should now be dead. Any voltage on it means it has rubbed through into a powered circuit, often where looms cross at the back of the engine or near add-on accessory wiring.
- Fix the open or replace the injector, then road-test
Repair any break or high-resistance spot with soldered, sealed joints, or replace the injector if its winding went open — relieve fuel pressure first and use new seals. Clear the code and recreate the freeze-frame conditions, since faults that need heat or vibration rarely show up on a short idle.
DIY or shop? A high-reading injector circuit is one of the friendlier faults to chase at home: most of the work is connector inspection, a noid light, and a multimeter, and the fix is often a single terminal or a short wire repair. Swapping a port injector on cylinder 7 is still within reach if you can relieve fuel pressure and get to the rail. Let a shop take over when the fault only appears hot and refuses to reproduce, when the circuit disappears into a sealed harness section, or when the engine uses direct injection.
Tools for the DIY steps: Noid light set · Digital multimeter · Terminal test pins · Electrical contact cleaner · Wiring repair kit
Not sure which step applies to your car? Get the likely cause for your exact vehicle before buying anything for P0280.
Start a case with P0280 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 P0280?
Redline can’t determine from a symptom or code alone whether your car is safe to drive.
P0280: common questions
How is P0280 different from P0279?
They monitor the same cylinder 7 injector circuit in opposite directions. P0279 fires on low voltage (short to ground, shorted coil); P0280 fires on high voltage (open circuit, corrosion resistance, or a short to battery voltage). The direction tells the technician which failure modes to hunt.
Can corrosion really set this code?
Absolutely — it's one of the most frequent causes. Oxidized connector pins add resistance that distorts the voltage the ECM sees when it fires the injector. A visual inspection and cleaning of the cylinder 7 connector is a free first step that solves a surprising number of these.
Do I have to stop driving right away?
Redline can't make that call from the code alone. Every mile with an erratic cylinder 7 sends unburned fuel to the catalytic converter, so arrange the repair promptly rather than waiting. A flashing check-engine light or a strong misfire means the catalytic converter is at active risk — stop driving and park the car.
Why would this code appear and disappear?
Marginal connections behave that way: a corroded pin or nicked wire conducts normally until heat, moisture, or vibration breaks the contact, sets the code, then reconnects. Intermittent behavior is a strong clue to focus on the connector and harness rather than the injector body.
Related trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0280 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 P0280 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.