P0350: Ignition Coil Primary/Secondary Circuit/Open
Do not keep driving
Expect rough running and lost power. If the warning light is flashing, stop as soon as it is safe — unburnt fuel from dead cylinders damages the catalytic converter quickly.
What this code means
A fault in the ignition coil circuitry that the module could not attribute to a specific coil. Where a lettered code points at one cylinder, this general code more often points at what the coils share — the supply feed, a common ground, or the driver stage inside the module. Check the shared elements before testing coils individually.
Worth knowing what primary and secondary mean here, because the distinction narrows the fault: the primary side is the low-voltage circuit the module switches, and the secondary is the high-tension output to the plug. A primary fault is electrical and measurable; a secondary fault is usually insulation breaking down under load, which often only shows up when the engine is hot and working.
Likely causes
Start here
- Faulty ignition coil · easy
- Failed coil supply feed or relay · moderate
- Corroded or loose connector · easy
- Worn or fouled spark plugs · easy
Less common
- Blown fuse supplying the ignition circuit · easy
- Control module driver failure · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
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