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P0356 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.


P0356 is a generic trouble code found on vehicles made with an OBD-II (On-Board-Diagnostic) tool. This will include any vehicle made from 1996 to present. If you see this diagnostic trouble code (DTC), it indicates that there is a “Ignition Coil F Primary/Secondary Circuit Malfunction” that can happen for multiple reasons. Read about these helpful tips to better understand the ramifications of a P0356 code.


If a vehicle is modern enough to feature a PCM (Powertrain Control Module), then it’s definitely using a COP (Coil on Plug) ignition system. With a COP, each of the vehicle’s cylinders has its own coil. These coils are all controlled by the PCM, which attaches to each with two wires. One of these wires is used as a battery feed and the other is the coil driver circuit. The PCM ungrounds and grounds this circuit to deactivate or activate the coil.

Amongst other things, this setup makes spark plug wires unnecessary. Instead, the coils sit right above their spark plugs. However, a COP is definitely not without its potential for problems and can present its own set of difficulties.

P0356 is stored when the PCM detects an open or short with the driver coil dedicated to coil #6. In some vehicles, the PCM will actually go ahead and shut down this coil’s fuel injector to prevent further damage.


There are a few different explanations for why this code might show up. The simplest reason could be that the COP is faulty. Moisture intrusion from water or degreasers can sometimes be the cause for this. Next, it’s possible that the COP driver circuit is open, has a short to voltage, or is grounded.

If a bad COP isn’t the issue, check coil #6. It could be that there is a loose connection. In other cases, the #6 connector locks could be completely broken.


There are two main symptoms that generally accompany this code. The first and most common clue for this code is that the engine is misfiring. Listen for popping sounds or a backfire from the engine of your vehicle. 

Another indicator would be that your engine performance is intermittent. In other words, you may experience loss in engine power, rough idling, stalling or trouble with acceleration.

Usually, the Check Engine light will immediately be triggered when this code is registered, but some models may wait until several incidents occur before this happens or the code is logged. Instead of relying on your Check Engine light, it might be helpful to watch and listen to the symptoms your car is giving you prior to an alert from the Check Engine light. 


A mechanic will begin the diagnosis process by using an OBD-II scanner to download all the codes that have been stored. Next, they’ll check on the ignition coil and the ignition coil driver circuit for any signs of a problem. Any of the wires running into the PCM will have to be examined too. Finally, they’ll examine the connector to look for signs of corrosion or other types of damage.

Common mistakes

A lot of times, mechanics will rush to carry out a maintenance tune up. Although the vehicle may benefit from such a procedure, it won’t make the P0356 code clear. Unfortunately, a comprehensive diagnosis must be undertaken to truly pinpoint the problem (or problems) triggering this code.

How serious is this?

The problems associated with the P0356 code aren’t serious enough that it represents a threat to the life of your vehicle, but it can evolve into something that demands more expensive repairs if not dealt with right away. If nothing else, the owner will have to spend a lot more money at the pump because of an engine that is underperforming. It’s best not to procrastinate in figuring out the ultimate cause for this issue.

What repairs can fix the code?

repair manuals

The most common way to fix this code is to repair the ignition coil. The next likely solution is to repair a shorted or open wire in the ignition coil driver circuit. Lastly, if the connector has damage from corrosion, it may need cleaned, repaired, or completely replaced. In some cases, it will be necessary to completely replace an ignition coil or connector. 

Related codes

Similar codes to the P0356 are P0351, P0352, P0353 and P0354. These codes also indicate issues found in the ignition coil control circuit.


Although a P0356 code may not present an immediate risk, it is important to deal with the problem as soon as possible. Any issues related to the engine of a vehicle could result in permanent damage when left unattended. Thankfully, there are well-known fixes for the cause of this code. 

P0356 Code – What Does It Mean & How To Fix It