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OBD II Fault Code

  • OBD II P3421

OBD-II Code Decreased engine performance is defined as a Cylinder 3 Exhaust Valve Control Circuit/Open

In an effort to meet fuel and emissions standards, many manufacturers are utilizing cylinder deactivation systems. This system allows the engine's control module (PCM) to disable select cylinders when additional power is not needed from the engine, such as at idle or when cruising on the highway. If the engine's control module (PCM) determines that the Exhaust Valve for cylinder number three is not Turning on or off the way it is being commanded, the PCM will set code P3421.

Decreased engine performance Symptoms

  • Decreased engine performance
  • Increased fuel consumption

Common Problems That Trigger the P3421 Code

  • Engine oil level is too low
  • Powertrain Control Module (PCM) failure
  • Variable valve timing solenoid failure
  • Wiring issue
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