P0351 OBD Error Code: Problem & Solutions

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The P0351 fault code can be defined as Ignition Coil “A” Primary/Secondary Circuit Malfunction. Individual ignition coils are used by the ignition system on the vehicle for each cylinder. Each and every ignition coil is controlled by the engine control module. An ON/OFF signal is sent by the engine control module so that it can energize the ignition coil to create a spark at the spark plug when there is a requirement of spark at the cylinder.

It is the ignition system which would convert the battery voltage into the high voltage which is used to ignite the cylinder air/fuel mixture. The side of the system which provides low voltage is called the primary circuit. This would include the battery, ignition switch, primary coil winding, crankshaft sensor as well as ECU. On the other hand, the high voltage side of this system is known as secondary circuit. In the modern vehicles, it would include the coil pack as well as the spark plugs. The low primary circuit voltage is converted into the high secondary voltage with the help of coil pack which is needed to fire the plugs. The coil pack is generally a transformer which contains coils of wire inside it. In the primary side there are hundred turns of wire while the secondary side has thousands. Current would be then applied to the primary side of the coil, which would thus create a magnetic field around the winding. The current is then interrupted with the help of a switching device which is generally the PCM. This would cause the magnetic field to collapse, inducing the voltage into the winding. Similarly the collapsing magnetic field would create a voltage in the secondary winding. Since there are many more turns of wire in the secondary winding, then the output voltage would be increased to thousands of volts. This would be enough to ignite the spark plugs.

What causes this problem with the Ignition Coil “A” Primary/Secondary Circuit Malfunction?

• There can be short to voltage or ground on COP driver circuit
• Issue of open on COP driver circuit
• Loose connection at coil or broken connector locks
• The coil can be bad
• Defects in the powertrain control module
• Some quirks in the spark plugs or plug wiring
• The ignition coil might not be functioning properly
• There can be failed or failing ECU
• There can be open or short in the coil wiring harness
• Electrical connection might be poor
• Leakage in the intake manifold vacuum
• There can be a buildup of carbon in the throttle body air passages
• The idle air control valve or electronic body might turn out to be faulty
• Defaults in the ignition coil 1
• Ignition coil 1 harness might be opened or shorted
• There can be poor electrical connection in the ignition coil 1 circuit 

1. Ignition Coil - Did your mechanic just found out that there is some fault in the Ignition Coil? Buy top notch Ignition Coil from us at economical prices.
2. Powertrain Control Module - A broken Powertrain Control Module can cause a lot of issues. It would be nice if you get it replaced on time.
3. Engine Control Module - Everything is fine with the Ignition Coil and still OBD code P0351 flashing? Then there is definitely some fault with the Engine Control Module. Get it checked and replace if needed.
4. Fuel Ignition System - Fuel Ignition System parts are important car parts which should never be neglected. May be there is some fault in them due to which P0351 code may start flashing.
5. Engine Wiring Connector - A faulty Engine Wiring Connector can be troublesome. You can always rely on us as we have best auto parts for our customers.
6. Spark Plug - If everything is alright with Engine Wiring Connector, then there is surely some defect in Spark Plug. Get it replaced before the situation gets worse.
7. Electronic Control Unit - P0351 code can display due to some issues in the Electronic Control Unit. So, it is very important to replace the Electronic Control Unit with us at equitable prices.
8. Throttle Body - There can be some issues with the Throttle Body due to which you may see P0351 code appearing over and over again. Visit us to buy best quality Throttle Body online.

Our main motive is to achieve customer satisfaction as for us our customers are everything and that’s why we will help you to diagnose P0351 code by mentioning some major symptoms below:

Common Symptoms

• Engine might misfire on acceleration
• There can be hard to start condition of the engine
• Issue of engine hesitation
• The malfunction indicator lamp can start illuminating
• There can be lack of power in the engine, especially under heavy load
• Car engine may idle roughly

If you wish to correct this fault code, then you have to follow certain steps. Correcting a problem needs your careful attention. Here are some ways with the help of which you will be able to correct the OBD Code P0351:

• The faulty ignition coil should be replaced
• The damaged ECU should be replaced
• If you find out that there are some faults in the wiring harness, then it should be repaired or replaced as per the need
• You should replace the spark plugs and spark plug wiring
• Carefully repair the electrical connection fault

However, if you face any issue then we have stocked a wide range of best priced fusion, wiring diagram, battery connectors, fuse and more to help you out in fixing your car.

Here are some steps which you should follow in order to diagnose this fault code:

• A scanner should be used to check what codes are stored in the ECU, along with any freeze frame data for the codes
• All the codes should be cleared and carefully test drive the vehicle under similar conditions found in the freeze frame data to best duplicate the faults
• A visual inspection should be performed on the coil system and it's wiring, looking for any damaged as well as worn components
• Then you should use a scan tool to monitor the data stream information and determine if the fault is with a specific cylinder or all of the cylinders
• Then you should inspect the spark plug wire and plug, or the coil pack of the vehicle if the fault is with just one cylinder
• The primary ignition coil should be tested 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

Sometimes common mistakes are made when components are replaced without being test or all steps are not followed completely in the specific order. This would waste time as well as money for repairs. Have a look at some common mistakes which are made when diagnosing the P0351 fault code

• A lot of people might replace the Spark Plugs when in reality the issue can be leakage in the vacuum
• Replacing the ignition coil when cause of the malfunction was a vacuum leak