P0356: Ignition Coil F Primary Circuit Malfunction

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P0356 is a fault code that appears on automobiles that have been diagnosed using an OBD-II (On-Board-Diagnostic) instrument. This applies to any car manufactured between 1996 and the current. This error-detecting code (DTC) denotes an “Ignition Coil F Primary/Secondary Circuit Malfunction,” which can occur for various causes. Consider these useful tips to comprehend the repercussions of a P0356 code further.

P0356 Code Meaning

P0356 Code Meaning

If a car has a PCM (Powertrain Control Module), it is almost certainly equipped with a COP (Coil on Plug) starter motor. Every one of the car’s cylinders has a circuit with a COP. The PCM, which is connected to every coil via cables, controls them. The coil driving circuit is connected to one of these lines, serving as a battery bank. The PCM ungrounds and connects this circuit to disable or reactivate the coil.

This design eliminates the need for ignition system cables, among many other things. Rather, the coils are positioned directly above the fuel injectors. A COP, on the other hand, is not without its flaws and can provide its own set of challenges.

Whenever the PCM identifies an open circuit with the motor coil allocated to coil #6, P0356 is saved. The PCM in certain cars will turn off this coil’s gasoline injector to prevent additional harm.

Causes of P0356

There are several alternative reasons as to why this code appears. The simplest explanation is that the COP is defective. Sometimes this is caused by moisture absorption from rainwater or chemical solvents. The COP driver circuit could be open, low power, or ground.

Examine coil #6 if a bad COP isn’t the problem. There may be a faulty link. The #6 connector locking may also be destroyed in some circumstances.

  • Second cylinder coil packs cabling that is defective or damaged
  • Combustion circuit failure
  • Ignition plug with a defect
  • Stationary air control valve or mechanical body failure
  • The wire connecting the second cylinder coil pack to the PCM is broken or corroded.
  • The cabling or electric connection of the second cylinder coil pack is open or shorted.
  • Carbon accumulation in the Throttle Body’s air passageways causes an obstruction.
  • Pressure leakage in the inlet manifold
  • PCM with a bug (rare)

Symptoms of p0356

Two major symptoms usually accompany this code. The motor is seizing up, the primary and most prevalent symptom of this code. Look for bursting sounds or a misfire from your car.

One red flag is if your car’s efficiency is inconsistent. To put it another way, you might notice a reduction in engine speed, poor running, stopping, or difficulty with speed.

When this code is entered, the Engine Light is usually turned on right away. However, certain vehicles may delay until multiple occurrences have happened before this occurs or the code is recorded. Rather than depending on your Light Switch, it’s a good idea to pay attention to and heed the signs your automobile gives you before the Check Engine light comes on.

  • The Check Engine light illuminates the dashboard.
  • Ignition problems are either periodic or permanent.
  • Vibrations that are unusual when the vehicle is sitting or traveling
  • Speed is lost.
  • Engine performance deteriorates.
  • Malfunction in the engine
  • Gas mileage is poor.

Common mistakes

Specialists will frequently speed through a routine tune-up. Though this method may improve the car, it will not remove the P0356 code. Sadly, a thorough diagnostic is required to isolate the issue (or problems) that are causing this code.

Diagnosis P0356 ObdII code

Diagnosis P0356 ObdII code

A professional will start the diagnostic procedure by obtaining all stored codes with an OBD-II scanner. They’ll then look for any fault indicators with the ignition system and the combustion coil driver circuit. Any cables that run into the PCM will also need to be inspected. Lastly, they’ll inspect the connection for any signs of rusting or other damages.

  • Professionals begin repairing these error messages by measuring the resistance of the suspicious coil pack using a resistance test.
  • They will then examine the state of the ignition system electrodes.
  • The power level at the coil pack will then be measured.
  • They’ll then look for rust, bending, and even melt in the cables that link the coil packs.
  • The coil pack connection will then be checked to see if it receives proper ground supply.

How to Fix P0356 ObdII Code

Because code P0356 can appear in cars of various brands and models, you should always consult your car’s repair manual for precise repair instructions. If you’re not sure about your mechanical skills, hiring a mechanic is probably advisable.

If you insist on addressing the problems yourself, make sure your mechanical expertise is relevant. To understand how to fix code P0356, use a repair manual or an online service directory.

This error code’s solutions are quite easy and simple.

Pressure leaks must be repaired, such as leakages in the damaged vacuum line or the intake system gasket.

  • Coil pack replacement
  • Spark plug replacement
  • Any broken wire in the coil pack should be repaired or replaced.
  • Changing the PCM (rare)

How serious is this?

Error Code P0356 is a rather significant situation; for one thing, it causes numerous drivability problems, putting drivers of the car in danger. On the other hand, Malfunctions are always hazardous for the engine because they might destroy or block the catalytic converter.

And in this instance, the cylinders must work just as hard to keep the car running, placing stress on the cylinder and other related parts like fuel injectors, piston rings, and coil packs, leading them to wear out faster.

What fixes can you make to get rid of the error code?

The ignition coil is the most typical technique to fix this problem. Repairing a damaged or exposed wire in the igniting coil control circuit is the next most likely remedy.

Finally, if the connection has been rusted, it may need to be cleaned, fixed, or replaced entirely. A full combustion coil or connector replacement will be required in some circumstances.


However, a P0356 code may not pose a direct threat; it is critical to address the issue as quickly as feasible. If left untreated, any issues with a vehicle’s engine could result in irreparable damage. Thankfully, the source of this error has a well-known cure.

Toyota OBD2 CODE P0356
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