P0355 code: Ignition Coil E Primary/Secondary Circuit (Cylinder 5)
P0355 means ignition Coil E Primary/Secondary Circuit (Cylinder 5). The code says where to look, not what failed — the fix depends on which cause your car actually has.
What P0355 means
The ECM fires ignition Coil E — cylinder 5's coil — by switching its primary winding, and it monitors that circuit for the expected electrical signature on every spark event. P0355 sets when the circuit reads open or shorted, meaning the fault is electrical: the coil, its connector, or its wiring, as opposed to a worn spark plug that merely sparks weakly while the circuit stays intact. By definition this code only appears on engines with five or more cylinders, and where cylinder 5 physically sits depends entirely on the manufacturer's numbering — on many transverse V6 installations it lands on the rear bank against the firewall, which matters a lot for repair labor. Common causes are a failed coil, a corroded or loose connector, chafed harness wiring, or a blown fuse in the coil feed; a dead ECM coil driver is possible but uncommon. Expect the companion cylinder 5 misfire code, P0305, to be stored alongside it.
P0355 symptoms
- Persistent misfire on cylinder 5
- Rough idle and vibration through the cabin
- Flashing check-engine light under load
- Unburned-fuel smell from the exhaust
- Loss of power; misfire code P0305 usually accompanies it
What it costs to fix P0355
Typical range: $60–$550 · about ~0.2–3 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Ignition coil (single) | $30–$150 | ~0.2–3 hrs |
| Wiring or connector repair | $5–$50 | ~0.5–2 hrs |
| Spark plugs (while in there) | $20–$100 | ~0.5–1.5 hrs |
The coil itself is a modest part either way — what swings this repair is access. On an inline five- or six-cylinder, coil 5 is on top and labor is minimal (0.2–0.5 hr). On many transverse V6 engines, cylinder 5 is on the rear bank against the firewall and reaching it can require removing the upper intake manifold, pushing labor to 1–3 hours — which is also why shops often suggest doing all three rear plugs and coils while everything is apart.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0355 for my exact vehicle →
How to fix P0355
Moderate — doable at home with common tools and patience
- See whether other coil codes are stored
Before touching coil E, check what else is in memory. P0355 alone keeps the focus on cylinder 5's coil and its own wiring leg, but a cluster of coil codes on the same bank points at something those coils share — a fuse, relay, feed wire, or ground — and replacing one coil won't touch that.
- Look for water in the cylinder 5 plug well
When cylinder 5 sits on the rear bank under the cowl, a blocked cowl drain can dump rainwater onto the coils and into the plug well. Pull coil E and look for rust, standing water, or green corrosion in the connector; clear the cowl drains as well, or the replacement coil will drown the same way.
- Swap coil E with an easy-to-reach coil
Exchange the cylinder 5 coil with an easy-to-reach one, erase the codes, and run the engine through a warm-up and a drive. A circuit code that moves to the other cylinder's coil condemns the part; P0355 holding on cylinder 5 clears the coil and moves suspicion to its connector and harness.
- Voltage-drop test the coil feed and ground
Back-probe the coil 5 connector and, with the engine cranking or running, measure the drop between the battery and the feed pin, and on coils with a separate ground wire, between that pin and battery negative. More than a few tenths of a volt on either side means resistance in that path — often a corroded ground eyelet on the head or intake.
- Suspect the ECM driver only when all else passes
If a good coil, clean connector, sound feed, and solid ground still leave P0355 setting, the trigger wire back to the ECM or the driver inside it is what's left. Have that wire checked for an open or short to ground before anyone quotes a computer, and remember a shorted coil can kill a driver, so a new module needs a healthy coil.
DIY or shop? If cylinder 5 is on an inline engine or the front bank, the swap test and connector work make an easy afternoon. If your engine puts it on the rear bank of a transverse V6, getting a hand on coil E can mean removing the upper intake plenum — new gaskets, a torque sequence, and a vacuum leak if it goes back together carelessly. A home mechanic can still scan, read the code pattern, and clear the cowl drains. Hand it off when the plenum has to come off and you haven't done one before, or when the trail leads to the trigger wire or the computer.
Tools for the DIY steps: OBD-II scanner · Digital multimeter with back-probe pins · Socket set with extensions · Compressed air or shop towels for the well · Dielectric grease
Not sure which step applies to your car? Get the likely cause for your exact vehicle before buying anything for P0355.
Start a case with P0355 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 P0355?
Redline can’t determine from a symptom or code alone whether your car is safe to drive.
P0355: common questions
Why is fixing P0355 expensive on some V6 engines?
Not because of the part — a coil is cheap — but because of where cylinder 5 often sits. On many transverse V6 layouts it's on the rear bank, tight against the firewall, and getting a hand on the coil can require removing the upper intake manifold. That turns a 15-minute job into a 1–3 hour one, which is most of the bill.
Is P0355 the coil or the spark plug?
P0355 is a circuit code, so it points at the coil, connector, or wiring — not the plug. A worn plug causes misfires without breaking the circuit. Still, if the rear bank has to come apart to reach the coil, replacing the plugs back there at the same time is smart, because the labor to get at them is the expensive part.
Can I drive with P0355 until my appointment?
That's not something the code alone can answer. With a steady check-engine light, every mile feeds unburned fuel to the catalytic converter, so don't let it go for days — book the repair promptly. If the light starts flashing, that's active catalyst damage — stop driving and get it checked.
Which cylinder is number 5 on my engine?
It varies by manufacturer — there's no universal numbering. Some V6s number one bank 1-2-3 and the other 4-5-6; others alternate banks. Your owner's or service literature (or a quick lookup for your specific engine) tells you which physical cylinder is 5, which you'll want to know before doing a swap test.
Related trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0355 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 P0355 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.