Fault code P0356 – ignition coil “F” primary/secondary circuit malfunction

Fault code P0356 is called “Ignition Coil “F” Primary/Secondary Circuit Malfunction” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P0356

This Diagnostic Trouble Code (DTC) is a general powertrain code. Error P0356 is considered a general code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly depending on the model.

Fault code P0356 – ignition coil

The COP (coil on plug) ignition system is used in most modern engines. There is a separate coil for each cylinder, controlled by the PCM (transmission control module).

This eliminates the need for spark plug wires by placing the coil directly above the spark plug. Each coil is allocated two wires. One is the power supply, usually coming from the power distribution center. The other wire is the coil driver circuit from the PCM.

The PCM grounds/disconnects this circuit to activate or deactivate the coil. The coil driver circuit is monitored by the PCM for faults.

If an open or short circuit is detected in coil driver circuit number 6, error P0356 may occur. In addition, depending on the vehicle, the PCM may also trip the cylinder fuel injector.

Symptoms of vehicle malfunctions

The main signal that an error P0356 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. Check engine control lamp on the control panel will light up.
  2. Jerking, jerking engine when running
  3. Unstable operation, ignition skips at idle.
  4. The engine stalls or fails to start.
  5. Loss of power.

Fault P0356 is considered quite serious, since its occurrence may cause problems with the engine operation. If this code is detected, it is recommended to eliminate the fault as soon as possible.

Factors that can cause this error code

The error code P0356 can mean that one or more of the following problems have occurred:

  • Short-circuited or broken ignition coil wiring harness.
  • Poor electrical connection or an open circuit in the ignition coil.
  • Cables and connectors leading to the ignition coil may be defective. There may be features such as wear or friction on another component.
  • The ignition coil is defective.
  • The engine control module (ECM) is defective.

How to fix or reset OBD-2 code P0356

Some suggested steps for troubleshooting and fix the error code P0356:

  1. Check that the electrical connection in the coil connector is serviceable.
  2. If there is a motor malfunction, turn off the motor and disconnect the cables relating to coil #6. Then start the engine with the cables disconnected and use a voltmeter. It should show a range of 5 to 20 Hz, if this range is not present, replace the ignition coil.
  3. If there is no signal from the PCM in the ignition coil circuit, leave the coil disconnected and check the circuit drives at the ignition coil connector. Significant voltage means a short circuit. You need to locate it and make the necessary repairs.
  4. If there is no voltage in the driver circuit, disconnect the connector from the PCM. And check the continuity of the driver circuit between the transmission control module (PCM) and the coil. If there is no breakage, it indicates a ground fault. Fix the problem.
  5. If there is a breakage, check the resistance between the ground and the ignition coil connector. The result should be infinite resistance. If not, correct the ground fault in the coil driver circuit.

Diagnose and repair of problems

When starting the diagnosis of P0356, try to move and test the wiring at coil number 6 and along the wiring harness to the PCM. If manipulation of the wiring causes ignition skips, correct the wiring problem. Check for secure contact in the coil connector. Make sure the wire bundle is not rubbing against anything. Repair if necessary.

If the engine is currently experiencing an erratic operation, stop the engine and disconnect the #6 coil wiring connector. Then start the engine and check the driver signal on coil #6.

Use a voltmeter on the AC scale in hertz. See if there is a reading between 5 and 20 hertz or so, indicating that the driver is working. If the reading is different, replace ignition coil #6.

If there is no frequency signal from the PCM in the ignition coil driver circuit, leave the coil disconnected. Check the DC voltage in the driver circuit, at the ignition coil connector. If there is significant voltage on this wire, there is a short somewhere. Locate the short and correct it.

If there is no voltage in the driver circuit, turn off the ignition. Disconnect PCM connector and check for continuity between PCM and coil. If there is no continuity, repair the circuit breakage or short.

If an open circuit is present, check the resistance between the ground and the ignition coil connector. The resistance should be infinite. Other readings indicate a short, correct the ground fault in the coil driver circuit.

If you find that the engine is skipping ignition, the coil is triggering correctly, but code P0356 keeps showing up. There is a possibility that the PCM coil control system may be defective.

On which vehicles does this problem occur most frequently

Fault code P0356 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Audi
  • Cadillac
  • Chevrolet (Cruze)
  • Dodge (Intrepid)
  • Ford (F-150)
  • Hyundai
  • Jaguar
  • Jeep (Liberty)
  • Lexus (ES330, ES350, RX350)
  • Mercedes-Benz
  • Peugeot
  • Toyota (Avalon, Camry, Highlander, Prado, Sienna)
  • MAZ

Fault code P0356 can sometimes be found with other errors. The most common are the following: P0031, P0051, P0132, P0171, P0174, P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0351, P0352, P0353, P0354, P0355, P0506, P2195, P2197, C1201.


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