Question

What does the P3400 code mean? 

The engine error code P3400 means ‘Cylinder deactivation system – Bank 1.’ The code activates when the PCM recognizes a failure, or malfunction in any part of the cylinder deactivation system. 

Common causes of P3400 code 

The code P3400 can be registered in your vehicle due to one or more of the following reasons: 

• Faulty cylinder deactivation solenoid  
• Low level of oil  
• Contaminated, degraded, or unsuitable engine oil  
• Faulty, burnt, shorted, corroded, or disconnected wiring or electrical connectors  
• Malfunctioning or unsuitable Mass Airflow Sensor or Intake Air Temperature Sensor  
• Faulty or unsuitable Throttle Position Sensor  
• The lifters have poor oil pressure  
• Faulty lifters  
• An open or short circuit in the cylinder deactivation solenoid connection  
• A faulty electrical connection in the cylinder deactivation solenoid circuit  
• A malfunctioning VVT (Variable Valve Timing) oil control solenoid  
• Failure of the PCM or another control module. Though it is an uncommon occurrence, it requires looking for the fault elsewhere before replacing any control module. 

Symptoms of P3400 code 

Typical code P3400 symptoms are almost the same across all cars and may include one or more of the following: 

• Check engine light turns on  
• Engine starts vibrating  
• Engine performance goes down  
• A sharp increase in fuel consumption   
• The engine may run rough or stall regularly and suddenly  
• The PCM may initiate a fail-safe or limp mode in some instances, which will last until the fault gets rectified 

How to fix the P3400 code 

It is almost impossible to fix this trouble code by yourself unless you are a skilled mechanic. If not, get some professional help who can properly diagnose and fix the issue for you. Here are some of the common repairs that can fix this code: 

• Replacement of cylinder deactivation solenoid #1  
• Replacement of cylinder deactivation solenoid #7  
• Remove dirt and debris from cylinder deactivation solenoid oil passageways   
• Make lifter oil passageways free from dirt and debris  
• Replacement of engine lifters  
• If dirt and mud cover the entire engine, it will be necessary to disassemble the entire engine to clean it properly