01 Why Do They Ask for Your Old Car Battery? A Comprehensive G… • 02 P0068 - Throttle Body Airflow Performance (PCM) • 03 What should I do if my manual transmission is slipping or p… • 04 That Rotten Egg Smell From Your Exhaust Isn't Normal: Here'… • 05 AT Gearbox vs DSG Gearbox: What’s the Difference? • 06 Engine Timing: A Comprehensive Guide for Successful Adjustm… • 07 Most Owners Don’t Realize Their Infotainment Screens Are Se… • 08 Most Owners Don’t Realize Their Car’s Interior Lights Can D… • 09 The Flywheel: Understanding Its Parts, Functions, and Impor… • 10 The Single Component Under Your Hood That Could Be Draining… •

DTC codes / P34xx · Auxiliary emission controls / P3440

P3440Cylinder 5 Exhaust Valve Control Circuit High

P3440 indicates that the powertrain control module (PCM) has detected an abnormally high voltage on the control circuit for the cylinder 5 exhaust valve actuator. This typically means the circuit is open, shorted to voltage, or the actuator itself has failed, preventing the PCM from properly commanding the exhaust valve to open and close.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaAuxiliary emission controls

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms
  • Rough idle or misfire-like shudder, especially when the engine is cold
  • Reduced engine performance and poor fuel economy due to improper cylinder breathing
  • Increased emissions, which may cause a state inspection failure
  • In some cases, a noticeable ticking or tapping noise from the valve cover area

Common causes, most likely first

  1. Open circuit in the exhaust valve control wiring, such as a broken wire or disconnected connector
  2. Short to voltage on the control circuit, often from chafed wiring contacting a power source
  3. Failed cylinder 5 exhaust valve actuator solenoid
  4. Corroded or damaged electrical connector at the actuator or PCM
  5. Internal PCM driver failure for the cylinder 5 exhaust valve control circuit
  6. Mechanical binding of the exhaust valve mechanism, overloading the actuator and causing a high-current condition

How to diagnose and fix it

  1. Inspect the exhaust valve actuator connector and wiring for damage, corrosion, or loose pins
  2. Measure resistance of the exhaust valve actuator solenoid and compare to specification
  3. Check for short to voltage on the control circuit with a multimeter while wiggling the harness
  4. Verify continuity of the control circuit from the PCM to the actuator
  5. Test the PCM output signal with an oscilloscope or a noid light designed for the circuit
  6. If the actuator is faulty, replace it and clear the code
  7. If the PCM driver is confirmed faulty, replace or reprogram the PCM as needed

High Voltage Does Not Always Mean a Bad Actuator

  • A high voltage code often results from an open circuit rather than a short, because the PCM pulls the circuit high when it cannot detect the expected load.
  • Wiring harness damage near hot exhaust components is a common cause that is frequently overlooked during diagnosis.
  • The same code can be set by a mechanically stuck exhaust valve that overloads the actuator, so always check for free movement of the valve mechanism.
  • After repairs, the PCM may require a relearn procedure or several drive cycles before the code clears permanently.

Can I keep driving with P3440?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy acceleration or towing because the engine may enter limp mode. Prolonged driving with this code can damage the catalytic converter and increase repair costs.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

Running on fumes Free guides aren't free to make. Top up the tank. Any amount, one time. Fuel the Garage