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.
Two Trip Detection Logic
When a malfunction is detected for the first time, 1st trip DTC and 1st trip Freeze Frame data are saved in the ECM memory. The MIL will not illuminate at this stage. <1st trip>
If the same malfunction is detected again during the next drive, the DTC and Freeze Frame data are saved in the ECM memory, and the MIL illuminates. The MIL illuminates at the same time the DTC is saved. <2nd trip> The "trip" in the "Two Trip Detection Logic" means a driving mode in which self-diagnosis is performed during vehicle operation. Specific on board diagnostic items will cause the ECM to illuminate or blink the MIL, and save DTC and Freeze Frame data, even in the 1st trip, as shown below.
| x: Applicable -: Not applicable | ||||||||
|---|---|---|---|---|---|---|---|---|
| Items | MIL | DTC | 1st trip DTC | |||||
| 1st trip | 2nd trip | 1st trip displaying | 2nd trip displaying | 1st trip displaying | 2nd trip displaying | |||
| Blinking | Illuminated | Blinking | Illuminated | |||||
| Misfire (Possible three way catalyst damage) - DTC: P0300 - P0306 is being detected | x | - | - | - | - | - | x | - |
| Misfire (Possible three way catalyst damage) - DTC: P0300 - P0306 is being detected | - | - | x | - | - | x | - | - |
| One trip detection diagnoses (Refer to DTC INDEX ). | - | x | - | - | x | - | - | - |
| Except above | - | - | - | x | - | x | x | - |
When there is an open circuit on MIL circuit, the ECM cannot warn the driver by Illuminated MIL when there is malfunction on engine control system.
Therefore, when electrical controlled throttle and part of ECM related diagnoses are continuously detected as NG for 5 trips, ECM warns the driver that engine control system malfunctions and MIL circuit is open by means of operating fail-safe function.
The fail-safe function also operates when above diagnoses except MIL circuit are detected and demands the driver to repair the malfunction.
| Engine operating condition in fail-safe mode | Engine speed will not rise more than 2, 500 RPM due to the fuel cut |
NO RELATED
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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.