The P0351 diagnostic fault code is an OBD2 general fault code that indicates a fault with the ignition coil circuit ‘A.’ This code indicates that there may be a problem with the circuit or ignition coil in cylinder 1. There is a separate coil for each cylinder, controlled by the power train control module (PCM/ECM/ECU). The coils are mounted on top of spark plugs, eliminating the need for wires. Each coil has two wires for connection. The ECU uses the other wire. This wire is used by the ECU to activate or deactivate coils. The ECU will generate the P0351 error code if it detects that this wire is faulty. It may also turn off the fuel injection going to the cylinder, depending on the vehicle’s make.
All ignition coils are equipped with a primary and secondary winding. The two windings nest together, with an iron core in the middle. The purpose of this is to increase the magnetic field. The primary winding is responsible for generating the high voltage spark needed by the secondary winding. The ECU directs the primary winding conduct current. At the moment of ignition, the ECU interrupts the current to generate approximately 20-30 thousands volts on the secondary winding.
To ensure proper ignition, the ECU must monitor circuit A continuously. It will generate the P0351 error code if it is unable to receive the signals required from this circuit. The engine fault light will also illuminate if it does not receive the necessary signal.
Table of Contents
What are the possible causes of fault code P0351?
- Faulty Spark Plugs or spark plug Wires
- Faulty Ignition Coil(s)
- Problems relating to the ignition coil circuit
- Weak electrical connections
- Camshaft sensor problems (rarely).
- ECU/ECM/PCM that requires updating or is faulty (rarely).
What are the symptoms of fault code P0351?
- The engine fault lamp is illuminated (sometimes, there are no other symptoms).
- Misfiring engine
- Irregular idle
- Engine hesitation during sudden acceleration
- Power loss, especially under load
How to Fix Fault Code P0351?
Before repairing the vehicle, it is necessary to clear fault codes and test it. Visually inspect the ignition coils and cables. Use a scan tool to determine if the problem is on one or all of the cylinders. Check the spark plugs and cables. The primary ignition coil must be checked if all cylinders have a fault. The ECU must be tested if no faults are observed.
- Replace spark plugs, spark plug wires
- Replacement ignition coils
- Repair of wiring harnesses
- Correction of electrical faults
- Replacement of ECU
How Important is Fault Code P0351?
The severity of the fault code P0351 is determined by the symptoms. The symptoms can make driving the car unsafe if they are severe. This code will not stop the vehicle from being operated, but it is important that you repair it as soon as possible.
Notes Regarding Fault Code P0351
The computer of your vehicle may set fault codes such as P0351 to P0358 if it detects an ignition coil problem. These codes are identified by the last digit. The repair and diagnostic procedures can vary depending on which cylinder you are dealing with.
