OBD codes / P0359
P0359
SeriousIgnition Coil I Primary/Secondary Circuit (Cylinder 9)
With ten or twelve cylinders, one dead hole can be hard to feel — but cylinder 9's unburned fuel is still overheating the catalytic converter on its bank. Don't let smoothness fool you into ignoring it. A flashing check-engine light means active catalyst damage: drive minimally and gently until it's repaired.
What this code means
This code reports an electrical fault — open or short — in the circuit of ignition Coil I, the coil for cylinder 9. Since it requires a ninth cylinder, P0359 only exists in practice on V10 and V12 engines; if it appears on anything smaller, suspect a scan-tool misread. The ECM triggers each coil by switching its primary winding and monitors the circuit's response every firing event, so the code is specific: coil I's circuit failed electrically, which is a different failure mode from a worn spark plug (a plug degrades the spark without breaking the circuit). Causes follow the familiar pattern — a failed coil, a loose or corroded connector, chafed wiring in that bank's harness, a blown fuse in the coil supply, or rarely the ECM's coil driver. Because cylinder 9 loses spark, its companion misfire code P0309 usually sets as well; on a ten- or twelve-cylinder engine the miss can be subtle at idle, so the codes may be the only obvious evidence.
Symptoms you might notice
- Misfire on cylinder 9 — may feel subtle on a V10/V12
- Slightly uneven idle or faint periodic shudder
- Check-engine light, flashing under load while misfiring
- Fuel smell from the exhaust
- Reduced power; typically paired with P0309
What it costs to fix
Typical range: $70–$500 · about ~0.3–2.5 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Ignition coil (single) | $30–$150 | ~0.3–1.5 hrs |
| Wiring or connector repair | $5–$50 | ~0.5–2 hrs |
| Spark plugs (while in there) | $20–$100 | ~0.5–1.5 hrs |
V10 and V12 engine bays are usually crowded — coils can hide under covers, plumbing, or cowl panels — so labor runs longer than on a simple four-cylinder even though the coil itself is a similar modest part. On these engines it's common to at least inspect the neighboring coils and plugs while the covers are off, since they share age and heat exposure.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0359 for my exact vehicle →
Frequently asked
What engines can even set P0359?
Only engines with nine or more cylinders — in practice V10s and V12s, since coil I serves cylinder 9. If this code shows up on a four-, six-, or eight-cylinder vehicle, the code was misread or the scan tool glitched; there is no coil I to fault.
Why can't I feel the misfire if P0359 and P0309 are set?
On a V10 or V12, the remaining cylinders smooth over one missing firing pulse far better than a four-cylinder could, so the misfire can be nearly imperceptible at idle. The damage still happens, though — unburned fuel from cylinder 9 is heating the catalytic converter whether you feel the miss or not.
Is P0359 expensive to repair on a V12?
The coil is an ordinary, modestly priced part — the variable is labor, because many-cylinder engine bays bury coils under covers and plumbing. Expect more shop time than a four-cylinder coil job, and consider having the neighboring bank hardware inspected while it's open to avoid paying the access labor twice.
Can I drive until the repair?
Short, light-throttle driving with a steady check-engine light is generally tolerable. A flashing light means the converter on that bank is being damaged right now — park it or drive as little and as gently as possible until it's fixed.
Seeing P0359 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0359 for my vehicleRelated trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0359 from your phone — see our honest guide to the best OBD2 Bluetooth adapters.
Generic OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.