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.
Reading Self-Test Codes: Notes
During Self-Test procedures, service codes are transmitted to the Self-Test Output connector by the ECA. All service codes are 2 digit numbers which are generated 1 digit at a time. Codes are shown as voltage pulses (needle sweeps) on an analog volt/ohmmeter (VOM). If a STAR (Self Test Automatic Readout) tester is used, it will count the pulses and display them as a digital code. The STAR tester will add a 0 to single digit (separator and dynamic response) codes.
Codes are shown as sequential groups of three codes. The sequence of groups varies, depending upon which test is being performed. If a VOM is being used, careful attention to the length of the pauses is necessary in order to read the codes correctly. There will be a 2 second pause between each digit in a code. There will be a 4 second pause between each code. There is a minimum 6 second pause before and after separator and dynamic response codes.
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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.