Wondering why the check engine light is on?

For many people, diagnosing what is wrong with a vehicle is a daunting task. Luckily, most modern vehicles are built with a system of codes to make it much easier. Mechanics use special devices which communicate with the car and get a particular code, which corresponds to the exact issue the car has. Anyone can use one of these devices, however. The only trick is knowing what the code means. The OBD-II scanner error code P3400 problem relates to the cylinder deactivation system. If you are like many people, this does not mean anything to you, but we can explain exactly what error code P3400 means for your car and what you can do about it.

What Does P3400 Mean?

The cylinder deactivation system malfunctioning is a pretty confusing concept. So, what does the code P3400 mean? You probably know that the cylinders are the part of the engine that actually creates power. If all the cylinders are running, then it means the engine is running at full power. Most vehicles have four cylinders, but many have six or eight. If a car has more cylinders, then it might have a cylinder deactivation system. It is not always beneficial to have all the cylinders running all the time. When your car is just cruising or has a low throttle, just four cylinders will get the job done just fine. The cylinder deactivation system prevents a few of the cylinders from firing, which saves fuel and saves you money.

The cylinder deactivation system functions by doing two things:

  • Close the valves
  • Disable fuel flow

Specifically, the cylinder deactivation system closes the intake and the exhaust valves for the unneeded cylinders. The valves need to be closed properly, because very small explosions happen inside the cylinders. It is a very delicate and powerful piece of machinery. Fuel flow being disabled is simpler and easier to understand. The whole point of deactivating the cylinders is to save fuel economy, which can only be done if the cylinders stop receiving fuel.

What Are The Symptoms of P3400?

There are only a few symptoms associated with this error code, and most of them are quite subtle. If the cylinder deactivation system cannot turn on, or if it turns on when it is not supposed to, it should turn on your check engine light. In all likelihood, this is the biggest warning you will get that something is wrong. However, you may be able to figure out that the cylinder deactivation system is malfunctioning if you experience:

  • Loss of fuel efficiency
  • Loss of power
  • Worse engine performance
  • The Solutions

Now for the answer to the most important question: “How do I fix trouble code P3400?” The most common cause of this problem is low oil level or pressure. Start by checking your oil levels and put more oil in if necessary. If that does not solve the issue, then you should have a manual oil pressure test done. Afterward, you can try driving the vehicle and see if the code reappears. If it does, then the problem most likely is a damaged or defective part. It will likely be a valve timing control solenoid or cylinder deactivation circuit. You should only attempt to replace these parts if you are very confident digging around in your engine. Chances are you will need a mechanic to take care of it, because these parts are hidden behind many others.

What Happens If You Ignore P3400?

There is very little inherent danger in the cylinder deactivation system malfunctioning. It will only result in poor fuel efficiency. However, the most common causes of this system malfunctioning can also cause extremely serious engine problems. If these go untreated, your entire engine may go, which can injure you or be very expensive to fix.

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