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P0351 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.

Definition

The OBD II error Code P0351 is defined as Ignition Coil ‘A’ Primary/Secondary Circuit Malfunction

Meaning

When the Powertrain Control Module (PCM) detects that the ignition coil of cylinder 1 or its circuit is faulty, it will set DTC P0351. Individual ignition coils for each cylinder are used in modern engines' ignition systems. Each ignition coil is monitored and controlled by the PCM.

There are two windings in every ignition coil: a "primary" winding and a "secondary" winding. The primary winding of an ignition coil is triggered by a coil pack circuit  allowing the secondary winding to generate the required high voltage spark to ignite the spark plug

The vehicle's ignition system uses individual ignition coils for each cylinder and the engine control module (ECM) controls all operation of the ignition coil. The ECM sends an ON / OFF signal to energize the ignition coil to create a spark at the spark plug when a spark is needed in the cylinder. If the ECM found the primary spike mild then it knows that the second section of the ignition coil is shorted out and the defect is on cylinder #1, the code P0351 is usually set at that point.

The cylinder with the  fault is indicated by the code's last digit. As a result, P0351 is the code for cylinder 1 (ignition coil A), P0352 is the code for cylinder 2, P0353 is the code for cylinder 3 and so on.

Causes

The P0351 error code can be caused by a variety of factors.

These are some of them:

  • Faulty ignition coils
  • Issues with the ignition circuit
  • Fault in spark plug or spark plug wire
  • In the ignition coil wire harness, there is an open or a short
  • Coil wiring connector with a flaw
  • Carbon build-up in the throttle body's air passageways

Symptoms

With the P0351 code, your car may show more than one symptom.

The following are the ones you're most likely to encounter:

  • The Check Engine light (Malfunction Indicator Lamp) illuminates on the dashboard
  •  Sometimes or all the time, the engine runs and idles roughly
  • Engine misfires on a regular basis or irregularly
  • The engine is underpowered, especially when under load
  • The vehicle is having problems starting

Diagnosis

  • Check what codes are saved in the ECU, as well as any freeze frame data for the codes, with a scanner
  • To best recreate the defects, clear the codes and test drive the car under conditions similar to those seen in the freeze frame data
  • Look for any damaged or worn components in the coil system and its wiring during a visual inspection
  • Use the scan tool to look at the data stream information and see if the problem is with one cylinder or all of them
  • If the problem is with just one cylinder, check the spark plug wire and plug, or the vehicle's coil pack
  • If all of the cylinders are faulty , check the primary ignition coil for good operation
  • If no fault has been identified up to this point, test the ECU

Common mistakes

When components are replaced without being tested, or when all stages are not completed in the correct order, mistakes are caused. This wastes both time and money in the repair process.

Many individuals mistakenly believe that the problem is with the spark plugs when, in fact, the problem is with vacuum leaks.

When a vacuum leak was the source of the malfunction and the ignition coil was replaced.

How serious is this?

Depending on how severe the symptoms are, the P0351 code can cause drivability issues that makes driving unsafe. Although this code should not prohibit the vehicle from being driven to a safe location, it should be rectified as soon as possible to restore normal vehicle performance.

What repairs can fix the code?

Repair manuals

The types of repairs for the P0351 code depend on what caused it in the first place.

The following are examples of possible repairs:

  • The ignition coil must be replaced
  • An ignition coil connector can be repaired or replaced
  • Any other electrical wiring or connector flaws will be repaired
  • The throttle body must be replaced
  • The PCM needs to be fixed or change

Related codes

  • P0352: Ignition coil control circuit – Cylinder 2
  • P0353: Ignition coil control circuit – Cylinder 3
  • P0354: Ignition coil control circuit – Cylinder 4
  • P0355: Ignition coil control circuit – Cylinder 5
  • P0356: Ignition coil control circuit – Cylinder 6
  • P0357: Ignition coil control circuit – Cylinder 7
  • P0358: Ignition coil control circuit – Cylinder 8
  • P0359: Ignition coil control circuit – Cylinder 9
  • P0360: Ignition coil control circuit – Cylinder 10
  • P0361: Ignition coil control circuit – Cylinder 11
  • P0362: Ignition coil control circuit – Cylinder 12

Conclusion

The P0351 code can be caused by a variety of factors, and a broken ignition coil should not be ignored for long. Remember that your engine is the heart of your vehicle, thus any engine problems, whether it's a coil driver circuit short, a broken fuel injector, or a faulty fuel pump, should always be handled by a professional.

P0351 code – what does it mean & how to fix it

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