2006 Mazda MX-5 Miata BaseFACTORY OEM SERVICE PROCEDURE

DTC P0638: Notes

DETECTION CONDITION AND POSSIBLE CAUSE (DTC P0638)

DTC P0638 Throttle actuator control circuit range/performance problem
DETECTION CONDITION 
  • The PCM compares the actual TP with the target TP when the engine is running. If the difference is more than the specification, the PCM determines that there is a throttle actuator control circuit range/performance problem.
Diagnostic support note 
  • This is a continuous monitor (CCM).
  • The MIL illuminates if the PCM detects the above malfunction condition during the first drive cycle.
  • PENDING CODE is available if the PCM detects the above malfunction condition.
  • FREEZE FRAME DATA is available.
  • The DTC is stored in the PCM memory.
POSSIBLE CAUSE 
  • Throttle actuator malfunction
  • Throttle valve malfunction
  • PCM malfunction
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.