1983 Honda Prelude AutomaticFACTORY OEM SERVICE PROCEDURE

Cold Engine

NOTE: Engine coolant temperature must be below thermosensor set temperature; thermosensor must have continuity.
  1. Disconnect vacuum hose from EGR valve and connect vacuum gauge to hose. Start engine and raise engine speed to 4500-5000 RPM. Vacuum should not be available.
  2. If vacuum is not available, proceed with Hot Engine test. If the gauge shows vacuum is available, check for voltage at EGR control solenoid valve A (Yellow/White).
  3. If there is voltage, replace EGR control solenoid valve A and retest. If there is no voltage, check thermosensor operation, wiring, fuses and retest.
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:

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

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