P0351 OBD-II Trouble Code: Ignition Coil "A" Primary/Secondary Circuit Malfunction

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P0351 code definition

P0351 is a general OBD2 diagnostic trouble code (DTC) that points to a fault with the ignition coil A.

What the P0351 code means

The P0351 DTC is seen when the ignition coil A primary or secondary circuit has a malfunction. The engine control module is looking for specific signals from the ignition coil A and when these signals are not seen the ECU sets the Check Engine Light. The Check Engine Light will be illuminated on the dashboard.

What causes the P0351 code?

  • Faulty spark plugs or plug wiring
  • Defective ignition coil
  • Failed or failing ECU
  • Open or short in the coil wiring harness
  • Electrical connection that is poor

What are the symptoms of the P0351 code?

  • Check Engine Light illuminating on dashboard
  • Engine is misfiring
  • Vehicle is hard to start
  • Engine has a lack of power, especially under heavy load
  • Erratic or rough idle

How does a mechanic diagnose the P0351 code?

  • Uses a scanner to check what codes are stored in the ECU, along with any freeze frame data for the codes

  • Clears the codes and test drives the vehicle under similar conditions found in the freeze frame data to best duplicate the faults

  • Performs a visual inspection on the coil system and it's wiring, looking for any damaged or worn components

  • Uses scan tool to monitor he data stream information and determine if the fault is with a specific cylinder or all of the cylinders

  • Inspects the spark plug wire and plug, or the coil pack of the vehicle if the fault is with just one cylinder

  • Tests the primary ignition coil for proper operation if all of the cylinders are faulty

  • Tests the ECU if no fault is found up until this point

Common mistakes when diagnosing the P0351 code

Mistakes are made when components are replaced without being test or all steps are not followed completely in the proper order. This wastes time and money for repairs.

How serious is the P0351 code?

The P0351 code can have some drivability symptoms that will not make it safe to drive depending on how severe the symptoms are. This code should not prevent the vehicle from being able to be driven to a safe location but should still be repaired ASAP for normal vehicle operation.

What repairs can fix the P0351 code?

  • Replacing the spark plugs and spark plug wiring
  • Replacing the ignition coil
  • Repairing the wiring harness
  • Repairing the electrical connection fault
  • Replacing the ECU

Additional comments for consideration regarding the P0351 code

The ability to view the live data stream of the vehicle is very important for the success of diagnosing the P0351 code. This aids technicians is finding intermittent faults that they would otherwise have no ability to noticed.

Need help with a P0351 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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