P3401 Code: Cylinder 1 Deactivation/Intake Valve Control Circuit Open

Most engines use a four-stroke cycle that begins with the intake stroke. During this stage, the intake valve opens and the piston inside the cylinder moves downward to draw in a mixture of air and fuel, kickstarting the combustion process. The intake valve and exhaust valves both close once the compression stroke begins. Then the exhaust valve opens to let spent exhaust gases out after the power stroke occurs.

Some modern engines have a cylinder deactivation system, in which some of the engine’s cylinders can be disabled on demand to improve fuel economy. In a typical cylinder deactivation system, the valves on the desired cylinder are disabled (usually by using special lifters) to prevent combustion. The powertrain control module (PCM) controls the cylinder, activating or deactivating it when needed. If the PCM detects an issue with the cylinder’s intake valve, on-board diagnostics (OBD) could log a P3401 code.

What Does the P3401 Code Mean?

Diagnostic trouble code P3401 stands for “Cylinder 1 Deactivation/Intake Valve Control Circuit Open.”

Low load conditions, such as idling or cruising on a highway, don’t require too much power from the engine, which means it’s unnecessary to activate all cylinders. In some cases, engines with six or eight cylinders will only require half the power.

With a cylinder deactivation system, it’s the job of the PCM to determine the right time to deactivate some cylinders, which is typically done using two-stage hydraulic valve lifters.

Once the PCM deactivates some of the cylinders, oil pressure will travel through a passage to depress a pin. This lets the lifter’s outer portion follow the contour of the cam while the inner portion keeps the valve closed.

If the PCM notices that cylinder #1 is not turning on or off as commanded, it will store a code P3401.

Note: The definition of code P3401 might be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

What are the Common Causes of the P3401 Code?

• Low engine oil level
• Faulty cylinder displacement solenoid
• Wiring issues
• PCM failure

What are the Common Symptoms of the P3401 Code?

• Illuminated check engine light
• Decreased engine performance
• Increased fuel consumption

How to Diagnose the P3401 Code

DTC P3401 is a generic powertrain code that can be logged in vehicles with an OBD-II system. While this might be the case, keep in mind that the steps for diagnosis and repair can vary, depending on vehicle specifications.

If you’re not familiar with the process of diagnosing trouble codes, it’s best to leave the job to the pros to ensure that all steps and protocols are followed correctly. But if you think you can handle this kind of task, then you can go ahead and do it yourself.

To help you out, here is a video you can watch to get an idea of what the process usually involves.

How to Fix the P3401 Code

Attempting to fix a P3401 code can be frustrating and confusing, especially if you’re unsure of what to look for or how to use the needed tools. Under these circumstances, it’s best to bring your vehicle to the nearest auto repair shop and have a certified mechanic perform the necessary repairs.

 But if you’re set on fixing your vehicle on your own, make sure you’re equipped with the right information before proceeding. You might want to check out guides like those from Chilton or an ALLDATA subscription to get vehicle-specific repair information before working on your sedan, SUV, or truck.