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.
Diagnostic Mode 08 - Request Control Of On-Board System, Test Or Component: Notes
Diagnostic Mode 08 is used to control the operation of an on-board system, test or component. A Mode 8 service can be used to turn on-board system ON or OFF, or to cycle an on-board system, test or component ON or OFF for a specific period of time. The service can also be used to request system status or to report test results.
Diagnostic Mode 08, TID $01
Diagnostic Mode 08, TID $01 is used to determine if the evaporative system may be leaking.
Depending on the scan tool being used, the function test in Diagnostic Mode 08 may or may not be able to be performed.
If the scan tool being used will operate Diagnostic Mode 08, perform the test below FUNCTION TEST .
If the scan tool being used will not operate Diagnostic Mode 08, refer to EVAP SYSTEM, CHECKING FOR LEAKS .
Always follow the manufacturers instructions for the scan tool being used.
Test requirements
- No DTCs stored in the DTC memory.
- Intake Air Temperature (IAT) maximum 60° C.
- Coolant temperature 80 -110° C.
- Throttle valve angle 12.0 - 16.0%.
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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.