Cars & Vehicles Auto Parts & Maintenance & Repairs

How to Troubleshoot a Service Engine Soon Light

    Pulling "Check Engine" Light Codes with a Scanner

    • 1). Locate the test port link under the dash, also called the Assembly Line Diagnostic Link (ALDL). It's a small, 12-16 point electrical port and it may have a plastic cover.

    • 2). Plug the scanner into the test port and turn the ignition key into the "On" position. The dash panel lights and radio will come on but the engine won't be cranked.

    • 3). Answer the prompts on the scanner screen to identify the make, model and year of your vehicle. Select the option to pull the "Service Engine" codes.

    Other Methods for Pulling "Service Engine" Codes

    • 1). Turn the ignition key on, then turn on and off rapidly in this succession: on, off, on, off, on. End with the key in the "On" position. Watch the "Check Engine" light. It will flash a series of times to indicate trouble codes stored within the computer. For instance, Code 23 will flash this way: flash, flash, pause, flash, flash, flash. Consult your owners manual to find out what the codes mean or click the provided link.

    • 2). Locate the ALDL under the dash. If you have a 12 pt. ALDL port, you can connect ports "A" and "B" to begin the diagnostic sequence. Use a jumper wire or an unbent paper clip to connect the ports and watch the "Check Engine" light for codes. This method won't work on 16 pt. ports.

    • 3). Turn the key on and depress the odometer trip and reset buttons at the same time. Codes read from the odometer display in vehicles with digital dash clusters.

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