P0350 Code: Ignition Coil Primary/Secondary Circuit

It’s the job of the ignition coil to ignite the mixture of air and fuel in the combustion chambers at the proper time and speed. Otherwise, the engine may experience issues like misfiring, stalling, and not starting.

The PCM regularly tests the ignition coils to make sure the parts are working  properly. If the control module detects a problem with one of the coils, a P0350 code will be logged.

What Does the P0350 Code Mean?

The diagnostic trouble code (DTC) P0350 indicates “Ignition Coil Primary/Secondary Circuit.”

Modern coil-on-plug ignition coils have a primary circuit and a secondary circuit. The primary circuit includes the primary windings inside the coil, an engine RPM sensor, and the PCM. In most cases, the crankshaft position (CK) sensor serves as the RPM sensor. The power needed to run this circuit comes from the car’s battery.

Meanwhile, the secondary circuit is made up of the spark plug and coil secondary windings. It is also powered by the battery.

The primary and secondary circuits control the ignition coil. If either of them fail, they can prevent the spark plug from igniting the air-fuel mixture. Depending on which circuit failed, it could cause problems like reducing or eliminating the secondary voltage output, weakening the spark, or damage the PCM.

The PCM regularly checks the ignition coil. If the computer comes across an issue with the coil’s primary or secondary circuit, it will set the generic powertrain code P0350.

You may also watch this video to understand how ignition coil works:

Note: The definition of code P0350 can differ according to the vehicle manufacturer. Check the appropriate repair manual or repair database for the exact code definition.

What are the Common Causes of the P0350 Code?

• Faulty ignition coil
• Circuit issues, such as damaged wires and poor connections
• Worn-out spark plugs
• An issue with the PCM, such as software in need of an update

What are the Common Symptoms of the P0350 Code?

• Illuminated check engine light
• Misfiring
• Poor engine performance
• Reduced fuel efficiency

How to Diagnose the P0350 Code

The P0350 code is a generic powertrain code that various makes and models can log. However, this does not mean that there is a one-size-fits-all solution to identify its underlying problem.

If you’re not confident about conducting diagnostic tests on your vehicle, it’s a good idea to bring it to a professional mechanic. Otherwise, you can go ahead and diagnose the issue yourself. To help you get started, here are some videos that can give you an idea of what the process might involve:

How to Fix the P0350 Code

Attempting to fix a P0350 code can become a challenging task if you don’t have the right tools and know-how to test the ignition coil. In most cases, it’s best to leave the job to professionals.
For DIYers with advanced technical knowledge and hands-on experience who prefer to test and replace their vehicle’s ignition coils on their own, it will be helpful to rely on the appropriate repair manual or refer to an online repair database.