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.
System Description
The PCM monitors engine operation. It also contains a self-diagnostic system which stores Diagnostic Trouble Codes (DTCs) and compares them to On-Board Diagnostics Generation II (OBD-II) standards.
The goal of OBD-II regulation is to provide vehicle with an on-board diagnostic system which is capable of continuously monitoring the efficiency of emission control systems, and to improve diagnosis and repair when system failures occur.
The Federal Test Procedure (FTP) sets maximum allowable emission standards. A Malfunction Indicator Light (MIL) must illuminate if a system or component either fails or deteriorates to a point where the vehicles emissions could rise to greater than 1 1/2 times FTP standards.
DTCs may only be retrieved using an On-Board Diagnostic (OBD-II) scan tool. Use of Tech 2 scan tool is recommended. Other suitable aftermarket scan tools are available.
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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.