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.
OBD-II System Readiness Tests
In some areas of the country, it may become a legal requirement to pass an Inspection/Maintenance (I/M) test of the OBD-II system. Before I/M testing can proceed, all of the System Readiness Tests (SRT) must show a YES status on scan tool. Follow scan tool manufacturer's instructions.
During the mixed city and highway driving involved in the OBD-II drive cycle, the diagnostic test will test certain parts of the OBD-II software and hardware used to control vehicle emissions. Some tests will run to completion and will indicate a YES or NO, others such as misfire or fuel injection system test, will run continuously. See SRT STATUS table.
| System Tested | Test Result |
|---|---|
| Misfire | Continuous |
| Fuel System | Continuous |
| Catalyst | No/Yes |
| Oxygen Sensor | No/Yes |
| Oxygen Sensor Heater | No/Yes |
| EVAP System | No/Yes |
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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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