OBD codes / P0350
P0350
SeriousIgnition Coil Primary/Secondary Circuit Malfunction
A coil circuit fault usually means at least one cylinder isn't firing, and every missed firing event dumps unburned fuel into the catalytic converter. With a steady check-engine light and mild symptoms, short careful driving is usually tolerable; a FLASHING light means the catalyst is being damaged — ease off, avoid load, and get it fixed promptly.
What this code means
The engine computer (ECM) fires each ignition coil by switching its primary circuit on and off, and it monitors that circuit to confirm the coil actually fired. P0350 is the general version of this fault: the ECM saw an open or short in a coil's primary or secondary circuit but did not (or could not) pin it to one specific coil, unlike P0351–P0362 which each name a cylinder. It is an ELECTRICAL fault — a break or short in the circuit — which is different from a worn spark plug that simply sparks weakly. Because it is unspecific, think in terms of things shared by all the coils: the fuse or relay that feeds them power, a chafed harness, a corroded common connector, or on some engines a single coil pack that serves multiple cylinders. A single failed coil or unplugged coil connector can also set it on systems that don't separate the fault by cylinder. Rarely, the coil driver inside the ECM itself is at fault.
Symptoms you might notice
- Engine misfire, stumble, or rough running — possibly on multiple cylinders
- Rough or shaky idle
- Check-engine light, flashing during an active misfire
- Hard starting or a no-start if a shared coil feed is dead
- Reduced power and worse fuel economy
- Often accompanied by misfire codes (P0300 or cylinder-specific P030X)
What it costs to fix
Typical range: $60–$450 · about ~0.2–3 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Ignition coil (single) | $30–$150 | ~0.2–0.5 hrs |
| Wiring or connector repair | $5–$50 | ~0.5–2 hrs |
| Spark plugs (while in there) | $20–$100 | ~0.5–1.5 hrs |
A blown fuse or unplugged connector is nearly free to fix; a coil is a modest part with quick labor on most inline engines. Costs climb when the fault is a chafed harness that takes diagnostic time to trace, or when coils sit under the intake manifold — rear-bank cylinders on transverse V6 engines can need intake removal, pushing labor to 1–3 hours.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0350 for my exact vehicle →
How to fix P0350
Moderate — doable at home with common tools and patience
- Check the ignition fuse and coil power feed
With the key on, verify the ignition-coil fuse is intact and that the coil connectors show battery voltage on the feed wire. A blown fuse or a dead power feed kills coil firing across the engine and is the cheapest possible outcome of this code.
- Inspect and wiggle-test the coil connectors
Unplug each coil connector and look for bent pins, green corrosion, oil intrusion, or melted plastic, then wiggle the harness gently with the engine running. A stumble during the wiggle test localizes an intermittent wiring fault.
- Identify which coil circuit is acting up
P0350 doesn't name a cylinder, so check for companion codes (P0351–P0358) and watch per-cylinder misfire counters in live data. The cylinder that misfires alongside this code points you to the suspect coil and its harness leg.
- Swap or replace the suspect coil
Once you've identified the offender, swap that coil with a neighbor and see if the fault moves with it. If it does, replace the coil; if it stays on the same cylinder, repair the wiring or connector on that leg instead.
- Have the ECM driver tested last
If the fuse, feed, connectors, wiring, and coil all check out, the coil driver inside the engine computer may be failing. That's rare and requires professional diagnosis — never replace an ECM without a shop confirming it.
DIY or shop? Fuse checks, connector inspection, and a coil swap are within reach of any home mechanic with a multimeter or test light. It becomes shop work when the fault is a chafed wire buried somewhere in the harness — tracing an intermittent electrical fault takes a wiring diagram and experience — and absolutely if the trail leads to the ECM itself.
Tools for the DIY steps: OBD-II scanner · Multimeter or test light · Small socket set for coil bolts · Electrical contact cleaner · Fuse puller
Not sure which step applies to your car? Get the likely cause for your exact vehicle before buying anything for P0350.
Frequently asked
What's the difference between P0350 and P0351–P0362?
They describe the same kind of fault — an electrical problem in an ignition coil circuit — but P0351 through P0362 name the specific coil (A through L, matching cylinders 1 through 12). P0350 is the generic version, set when the ECM can't isolate the fault to one coil, which often points to something shared: a fuse, relay, common connector, or harness feeding all the coils.
Is P0350 a bad spark plug?
No — this is an electrical circuit fault, not a worn plug. A tired spark plug sparks weakly but the circuit still measures fine; P0350 means the ECM detected an open or short in the coil wiring itself. That said, plugs are cheap and often replaced while the coils are out.
Can I drive with P0350?
Briefly and gently, if the check-engine light is steady and the engine runs mostly smooth. If the light flashes, an active misfire is sending raw fuel into the catalytic converter, which can ruin it — treat that as a stop-driving-soon situation.
What should be checked first for P0350?
Start with the cheap, common stuff: the fuse and relay that power the ignition coils, then each coil connector for looseness or corrosion, then the harness for chafing — especially where it passes near hot or moving parts. Only after the power and wiring check out is it worth condemning a coil or, very rarely, the ECM driver.
Seeing P0350 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0350 for my vehicleRelated trouble codes
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Generic OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.