Thread: SAI question
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Old 01-06-2019, 12:24 PM   #2
911monty
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Join Date: Oct 2014
Location: California Central Coast
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Garage
If a malfunction is detected during the 1st trip, the first trip DTC is stored in the ECM memory. The MIL light will not light up (two trip detection logic) If the same malfunction is not detected in the second trip, the 1st trip DTC is cleared from ECM memory. If the same malfunction is detected in the 2nd trip, both the 1st trip DTC and 2nd trip DTC are stored in the ECM memory and the MIL lights up.

In other words, the DTC is stored in the ECM memory and the MIL lights up when the same malfunction occurs in two consecutive completed trips.

When the MIL is set freeze frame data is also stored to help in troubleshooting.

Good Luck
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