P3400 Code – Meaning, Symptoms ,Causes And How To Fix It?

Written By: Terrence Hines
Category: Error Code

The P3400 code indicates a malfunction in the cylinder deactivation system and potentially poses a serious threat to vehicle performance.

This code can make your car use more gas and cause the engine to shake or run roughly. Be aware of this code so you can fix the problem if it comes up.

What Does The P3400 Code Mean?

P3400 is a diagnostic trouble code that indicates a problem with the cylinder deactivation system.

This system allows certain cylinders in the engine to shut down when not needed, decreasing fuel consumption during light-load use.

P3400 can make your car use more gas, produce more pollution, and have difficulty firing the engine in the damaged cylinder.

What Does The P3400 Code Mean?

Diagnosing P3400 requires hooking up a scan tool to retrieve stored codes and view live data from the deactivation solenoids.

It may require further inspection of the parts related to the solenoids or other components to identify any mechanical failure or wiring issues causing P3400.

To prevent P3400 from coming back in the future, it is important to double-check all repairs and remember to recycle any old fluids when replacing them with new ones.

Symptoms Of The P3400 Code

P3400 code, related to the cylinder deactivation system, is a trouble code that can sometimes cause significant damage to the vehicle.

Symptoms of P3400 could include hesitation or jerking when accelerating, reduced power and fuel efficiency, or stalling of the engine.

Other vehicle components might be damaged if the P3400 code is not addressed on time.

Car owners need to pay close attention to their car’s performance, so any signs of P3400 should be addressed immediately by a certified professional.

1. Engine Misfires In One Or More Cylinders:

P3400 code can be a frustrating problem to diagnose. One of the most common symptoms that indicate the P3400 code is engine misfires in one or more cylinders.

This code means there is a problem. To find the problem, use a diagnostic tool like an OBD2 Scanner. Once you find the problem, you can fix it.

P3400 code should not be taken lightly: if left unattended, it can cause further damage to your vehicle’s engine and performance.

Thus, having the code diagnosed by a professional mechanic as soon as possible is important.

2. Reduced Gas Mileage:

P3400 is a code many drivers experience at some point, signaling an issue with the cylinder deactivation system.

While P3400 codes can vary in severity, one common symptom is reduced gas mileage.

If P3400 occurs suddenly and disrupts your vehicle’s performance, it’s likely indicative of a larger problem, and you should consult an automotive specialist as soon as possible.

In many cases, P3400 can be resolved without major work but must be taken care of to avoid any further consequences on your vehicle’s overall performance.

3. Increased Emissions:

The P3400 code, the cylinder deactivation system, can be identified as the culprit behind increased emissions.

 Increased Emissions

This code indicates an imbalance in the number of cylinders activated compared to the original design specifications.

The P3400 code means that one or more cylinders are not working right. This makes the car release more harmful gases into the air. You should fix this problem as soon as possible.

By correcting any faults relating to P3400, we can help protect our air quality while keeping emissions low.

4. P3400 Code Retrieved From The Scan Tool:

P3400 is a code retrieved from the scan tool of your vehicle, which can be a symptom of a cylinder deactivation system.

This code typically indicates an issue with the camshaft actuators in the engine, which can prevent operations such as accelerating or changing gears.

A P3400 Code is most likely to appear when driving conditions are at the highest and components in the engine have become unstable.

In this case, you may have trouble diagnosing what’s wrong, and it’s best to visit a professional mechanic to get to the bottom of it quickly and safely.

5. Unusual Noises Coming From The Engine:

If you hear strange noises from your engine, it may be a symptom of the P3400 code.

P3400 code refers to a cylinder deactivation system that allows the powertrain control module to temporarily disable one bank of cylinders in certain conditions to improve efficiency.

If it is malfunctioning, you could start noticing unusual noises from your engine and decreased fuel efficiency.

It is important to get the P3400 code checked out immediately with a mechanic if you hear strange noises, as it is crucial for your vehicle’s proper function and safety.

Common Problems That Can Cause The P3400 Code

P3400 is a trouble code indicating an issue with the cylinder deactivation system in your vehicle, which can cause various issues.

If a P3400 trouble code is detected, it typically means that one or more components related to the cylinder deactivation system have gone bad.

Common problems linked to P3400 codes are faulty solenoid valves, worn camshaft actuators, exhaust gas recirculation valve sticking, oil control valve sticking, and poor electrical grounds.

Aside from the faulty Oil Control Valve and harness, an overheated or foreign-infested PCM may also be accountable for this phenomenon.

It’s important to investigate the manifold absolute pressure sensor. This will help to prevent P3400 codes from becoming bigger problems in the future.

1. Faulty Solenoid Valves:

P3400 code indicates a problem with the cylinder deactivation system in your vehicle.

It can be caused by faulty solenoid valves that control the switchover from four-cylinder to eight-cylinder mode.

Often this P3400 code can be difficult to diagnose, making it important to rely on your trusted mechanic for an accurate assessment.

Faulty solenoid valves will cause oil pressure in the external hydraulic circuits to increase, thus triggering P3400 code activation.

If you have a problem with the P3400 code, ask for help from a professional immediately.

The P3400 Code

If you keep driving with this code, it could cause more problems like bad gas mileage or spark plugs that do not work well.

2. Worn Camshaft Actuators:

 Worn camshaft actuators can be the root cause of P3400 codes as they control the valve system inside the engine and allow for cylinders to be shut off when needed.

This P3400 code is known to be due to this worn component which could cause reduced motors efficiency and make fuel economy suffer.

Any P3400 code must be checked by a professional as soon as possible to identify if it is related to a worn camshaft actuator and address the problem accordingly.

3. Exhaust Gas Recirculation Valve Sticking:

A P3400 code in a vehicle can be caused by a sticking exhaust gas recirculation (EGR) valve. This EGR valve works to reduce excess emissions in the automobile’s combustion chamber.

When it gets stuck, it can not do its job effectively, resulting in the P3400 code activating, a decrease in fuel economy, and increased pollutant levels.

It is important to fix this issue as soon as possible to reduce further damage to your vehicle and the environment.

4. Oil Control Valve Sticking:

P3400 code is a common fault in vehicles with a cylinder deactivation system.

This system allows the vehicle to switch off certain cylinders when not needed for better fuel efficiency but can cause an issue when the oil control valve becomes stuck.

The P3400 code is triggered when the oil control valve fails to deactivate or activate correctly and can lead to other faults if left unchecked.

It is important to check your vehicle’s oil control valve regularly. This will help prevent the P3400 code from happening, which might cause other problems if it’s not fixed early.

5. Poor Electrical Grounds:

P3400 codes are a sign of trouble with the cylinder deactivation system in a vehicle, and poor electrical grounds are often to blame.

This means that the current isn’t effectively reaching all the systems necessary for the cylinder deactivation function, resulting in the P3400 code being thrown.

To ensure your cylinder deactivation system is running optimally, check your electrical grounds and ensure they are free from corrosion or any other damage.

Poor Electrical Grounds

Once this is addressed, P3400 codes should be eliminated – allowing your engine to run correctly again!

How To Fix The P3400 Code?

P3400 is an important code concerning the cylinder deactivation system within your vehicle.

If you encounter this issue, it’s best to diagnose and locate the root cause of this problem before attempting any repair.

The P3400 code is often caused by a malfunctioning pressure sensor near your engine’s camshaft; however, this could also be due to a faulty wire or an open circuit.

To fix this code, inspect the pressure sensor, change out clutch solenoid assemblies if they are not functioning properly, and eliminate any faulty wirings.

Additionally, use a consumable lubricant or silicone spray on the P3400 components as a preventative measure to keep P3400 from reappearing again.

Taking these steps should help you accurately identify and fix P3400 when it arises.


The P3400 code indicates a malfunction of the cylinder deactivation system. This issue can range from minor to major, causing problems such as engine misfires and power loss.

Fortunately, the P3400 code is usually caused by something simple like debris blocking an oil passage or an overly loose cap on the oil fill tube.

However, it is important never to assume the cause of the P3400 code and always seek professional assistance if you suspect this problem in your vehicle.

Identifying and fixing this issue promptly can save you from more serious and expensive damage in the long run – so take these steps seriously!

Terrence Hines

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