Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Key On/Engine Off (KOEO) Self-Test: Notes
Correct test results for system are dependent on the correct operation of several related non-EEC components and systems. It may be necessary to correct faults in these areas before EEC-IV will pass QUICK TEST .
Verify that vehicle has been properly prepared. See PREPARATION and EQUIPMENT HOOK-UP . Turn ignition on to start SELF-TEST. DO NOT depress throttle during test. Observe and record all service codes.
- If engine does not start, go to TEST A - NO START , step 1). If KEY ON/ENGINE OFF (KOEO) code and continuous memory indicate a pass (code 11), go to TIMING CHECK .
- If any KOEO code is displayed with continuous memory code 11, KOEO SELF-TEST indicates a fault. Record codes and go to TEST RESULTS & ACTION TO TAKE in this test.
- If any (KOEO) or any continuous memory code is displayed, (KOEO) SELF-TEST and continuous memory indicate a fault. Record codes, but DO NOT repair continuous memory codes at this time. All (KOEO) and KEY ON/ENGINE RUNNING (KOER) SELF-TEST codes MUST be repaired first. Go to TEST RESULTS & ACTION TO TAKE in this test.
- If (KOEO) code 11 displayed with ANY continuous memory code (except 15), continuous memory indicates a fault. Record codes, but DO NOT repair continuous memory codes at this time. (KOEO) and (KOER) SELF-TEST codes MUST be repaired first. Go to TIMING CHECK . If engine idles rough, go to DIAGNOSIS BY SYMPTOM TEST .
- If (KOEO) code 11 is displayed and continuous memory code is 15, go to TEST PP - NO CODES/CODES NOT LISTED , step 9). If no codes are displayed, repeat SELF-TEST to verify that no service codes are present. If codes are not displayed, go to TEST PP - NO CODES/CODES NOT LISTED , step 1).
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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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