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P0359 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


P0359 is a diagnostic trouble code (DTC) that relates to an issue in the ignition coil I primary/secondary circuit for cylinder 9. This code is part of the On-Board Diagnostics II (OBD-II) system used in modern vehicles to monitor and diagnose various engine and emission-related problems.


P0359 indicates that, for cylinder 9, there is a problem with the ignition coil I’s Primary Secondary circuit. The ignition coil’s responsibility is to generate a strong spark which must be ignited by an airfuel mixture in the cylinders of the engine.


The P0359 DTC code may be caused by several circumstances, including:

  • Ignition Coil Issues: The ignition coil for cylinder 9 is the most frequent source of problems.
  • Wiring Issues: Damaged or corroded wiring and connectors in the ignition coil circuit can lead to this code.
  • Spark Plug Problems: Worn or fouled spark plugs can affect the ignition coil’s performance.
  • ECM Problems: In rare cases, issues with the engine control module (ECM) can trigger this code.


Common symptoms associated with the P0359 code include:

  • Check Engine Light: The most obvious symptom is the illumination of the check engine light on the vehicle’s dashboard.
  • Engine Misfire: Cylinder 9 may misfire, resulting in rough engine operation and reduced power.
  • Low Fuel Economy: Low fuel economy may be caused by an ignition issue.
  • Stalling: In serious circumstances, the engine could abruptly stall.


The following actions are routinely taken by a mechanic to identify and validate the P0359 code:

  • Code Scan: To recover the recorded error codes, including P0359, use an OBD-II scanner.
  • Visual Inspection: Look for corrosion or damage in the wiring and connectors connected to the ignition coil.
  • TestingTesting the Ignition Coil: To ensure correct operation, test the ignition coil’s resistance and voltage output.
  • Spark Plug Inspection: Check the spark plug for fouling or wear and replace it if necessary.

Common mistakes

Common mistakes when dealing with the P0359 code include:

  • Replacing the Ignition Coil Unnecessarily: Mechanics might replace the ignition coil without verifying its functionality, which can be costly if the issue lies elsewhere.
  • Neglecting Wiring and Connectors: Failing to thoroughly inspect and repair damaged wiring or connectors can lead to recurring issues.

How serious is this?

The seriousness of P0359’s code is dependent on the magnitude of the problem. Although the vehicle is still capable of using this code, it could lead to decreased engine performance, malfunctioning, or possible failure. To prevent further damage and ensure optimum engine performance, it is recommended that this issue be addressed without delay.

What repairs can fix the codeS?

repair manuals

It might be essential to take the following steps to fix the P0359 error code:

  • Replacement of the Ignition Coil: If the ignition coil for Cylinder 9 is defective, a brand-new, high-quality coil should be installed in its stead.
  • Repair of wire and connections: In the ignition coil circuit, repair or replace any frayed, corroded, or damaged wire and connections.
  • Replacement of the Spark Plug: A worn-out or fouled spark plug has to be changed.
  • Replacement of the ECM: If the ECM is found to be the problem, it may need to be replaced or reprogrammed.

Related codes

Related codes that may accompany or be related to P0359 include:

  • P0351 to P0358: These codes relate to ignition coil circuit issues for cylinders 1 through 8, respectively.


The DTC code P0359 indicates that the primary and second circuits of cylinder 9 are having trouble with ignition coil I. While this may not always lead to immediate problems with the vehicle’s driveability, it could result in insufficient engine performance, engine failure, or stalling.

To optimize the functioning of the vehicle and prevent any further damage, this should be addressed promptly. Diagnostics and repairs are usually carried out by checking the ignition switch, electrical circuit, connecting cable, or sometimes the electronic control module to correct the problem.

P0359 Code – What Does It Mean & How To Fix It