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.
KOEO Self-Test
Ensure engine is warmed to normal operating temperature. If engine does not start (or stalls after starting), continue KOEO SELF-TEST . DO NOT depress throttle. Turn ignition off. Ensure test equipment is properly attached. Turn ignition on (engine off). Record all KOEO and Continuous Memory Codes.
If a Code 111 (pass code) is not retrieved, service KOEO codes. See DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS . If PCM will not output codes, go to CIRCUIT TEST QA . If diagnostic trouble codes are retrieved:
- If MIL/CHECK ENGINE light is on, service diagnostic trouble codes in order retrieved. See DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS .
- If Continuous Memory Code 215, 216, 217, 218, 222, 224, 232 or 238 is retrieved during KOEO SELF-TEST, see IGNITION SYSTEM in the SYSTEM/COMPONENT TESTS article.
- If vehicle has a no-start condition, go to CIRCUIT TEST AA (DI), CIRCUIT TEST AB (EI - low data rate) or CIRCUIT TEST AC (EI - high data rate).
- If vehicle displays a Code 111 (pass code) and does not have any symptoms described in previous steps, go to KOER SELF-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.