OBD-II trouble code
P0282: Cylinder 8 Injector Circuit Low
The engine computer measured lower-than-expected voltage on the cylinder 8 injector control wire — a short to ground, a shorted injector coil, or a driver fault. Before you touch anything, confirm where cylinder 8 actually is: GM and Ford put it on opposite sides of the engine.
Quick facts
- System
- Powertrain
- Category
- Fuel Injectors
- Severity
- Medium severity
- Drivable
- No — stop driving until repaired
- Repair cost range
- $50 – $1,500
- DIY difficulty
- Intermediate DIY
What does P0282 mean?
The engine control module (ECM) fires each injector by feeding battery voltage to one side of it and switching the ground on the other side for a precise number of milliseconds. Between pulses, the control wire should sit near battery voltage because the injector coil connects it back to the feed. The ECM watches that line, and P0282 sets when the voltage on the cylinder 8 injector control circuit reads low when it should be high.
Three faults produce that reading. The control wire is shorted to ground somewhere in the harness. The injector's own coil winding has shorted internally, collapsing the circuit resistance. Or the ECM's cylinder 8 injector driver — the transistor that does the switching — has failed shorted-on. The first two are far more common than the third, and the third should only be concluded after the wiring and the injector have both been cleared.
A hard short usually means cylinder 8 is either dead or being flooded, which is why this code is treated as a do-not-drive condition. Unburned fuel dumped into the exhaust is the fastest way to destroy a catalytic converter, and on a V8 the damage concentrates on the converter serving whichever bank cylinder 8 is on.
This code carries the single worst cylinder-numbering trap in the entire per-cylinder injector block, and getting it wrong means diagnosing the wrong side of the engine. On a GM small-block or LS-family V8 the passenger bank is numbered 2-4-6-8, so cylinder 8 is the rearmost cylinder on the PASSENGER side. On a Ford modular V8 the driver's bank is numbered 5-6-7-8, so cylinder 8 is the rearmost cylinder on the DRIVER'S side. Those two conventions place cylinder 8 on completely opposite banks. Chrysler and most import V8s follow the GM-style odd/even split, but there are exceptions, and transverse V8s and V10s add their own variations. Look up the numbering diagram for your specific engine before you remove a single bolt. The firing order will not help you here — it tells you when a cylinder fires, not where it lives.
One more practical note: cylinder 8 is, on almost every V8, at the very back of a bank. That is the hardest injector on the engine to reach, frequently under the cowl, against the firewall, or beneath the upper intake plenum. That makes it worth testing the control wire for a short to ground from the ECM connector end, with the injector unplugged, before committing to a teardown. Ten minutes with a meter can save two hours of disassembly.
Common causes
- Cylinder 8 injector control wire shorted to ground from chafing or a pinched harness
- Internally shorted cylinder 8 injector coil winding
- Corroded, wet, or damaged connector at the cylinder 8 injector
- Harness rubbed through where it passes near the intake manifold, exhaust, or a bracket at the rear of the bank
- Water intrusion at the rear of the engine bay from a leaking cowl seal, reaching the rearmost connector
- Wiring damaged during recent intake manifold, plenum, or valve cover work
- Failed cylinder 8 injector driver inside the ECM/PCM (uncommon — rule out everything else first)
Symptoms
- Check engine light on, often flashing if cylinder 8 is dead
- Rough idle and noticeable engine shake
- Significant power loss and hesitation on acceleration
- Companion cylinder 8 misfire code (P0308) and often P0300
- Raw fuel smell or black smoke if the injector is being held open
- Hard starting or extended cranking
- Poor fuel economy
Diagnostic steps
- 1.Record every stored code. A cylinder 8 misfire (P0308) alongside P0282 confirms the cylinder is genuinely affected rather than the code being a stray electrical report.
- 2.Confirm which physical cylinder your engine calls number 8 before touching anything. GM V8s put it at the rear of the PASSENGER bank; Ford modular V8s put it at the rear of the DRIVER'S bank.
- 3.Unplug the cylinder 8 injector and clear the code, then start the engine. If P0282 returns with the injector disconnected, the fault is in the wiring or the ECM, not the injector — and you have just saved yourself a teardown.
- 4.With the injector unplugged and the key off, measure resistance from the control wire to ground. Near zero indicates the short to ground; an open reading clears the wire.
- 5.Measure the injector's coil resistance and compare it against specification and against the other seven injectors. A reading well below the others indicates shorted windings.
- 6.Inspect the harness along its whole run at the rear of the bank, paying attention to anywhere it passes a bracket, the exhaust, or a manifold edge. Rear-of-engine harnesses see the most heat and the most cowl water.
- 7.Inspect the connector itself for green corrosion, moisture, spread terminals, or a partially seated lock.
- 8.Wiggle-test the harness and connector with the engine running while watching live data, to catch an intermittent short.
- 9.If the wiring and the injector both test good and the drive signal is still wrong, suspect the ECM injector driver — but confirm the first two paths thoroughly, because module replacement requires programming.
Repair cost
$50 – $1,500
A wiring or connector repair is often $50-$250, though a chafed harness at the back of the bank can take longer to reach and trace. A single fuel injector runs $60-$400 in parts plus 0.5-3 hours of labor, and cylinder 8 sits at the top of that labor range on nearly every V8 because it is the rearmost injector — on many engines the upper intake plenum has to come off, which adds gaskets. Direct-injection units cost more than port injectors. A failed ECM injector driver is uncommon and runs $500-$1,500 including programming. Diagnosis alone is typically $100-$180.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with fuel injector replacement preselected. Adjust labor rate and vehicle category to fit your situation.
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.