1987 Ford Mustang LX, 2D Hatchback, 5.0 E, AutomaticFACTORY OEM SERVICE PROCEDURE

Code Output

  1. Deactivate SELF-TEST (disconnect jumper wire). Start engine and run it at 2000 RPM for 2 minutes to warm up HEGO sensor. Turn engine off and wait 10 seconds
  2. Start engine. Insert jumper to activate SELF-TEST. The engine ID code will be displayed.
  3. If a Dynamic Response code occurs, briefly accelerate engine to wide open throttle (WOT). DO NOT  depress throttle during test unless a Dynamic Response code occurs. The KEY ON/ENGINE RUNNING (KOER) SELF-TEST  service codes will then be displayed. Observe and record all codes.
NOTE: On the 5.0L SEFI engine a service code 98 may appear instead of the engine ID code, indicating the need to obtain a code 11 for the KEY ON/ENGINE OFF (KOEO) SELF-TEST  portion of the QUICK TEST  .
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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.

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