15/07/2026 8:38 am
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Automotive Q&A
Kia Niro repeatedly needs the 12V Battery Reset after sitting overnight
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A 2019 Niro hybrid powers up after using the 12V Battery Reset button, then operates normally. The low-voltage system charges correctly in Ready mode. After shutdown, current sometimes remains near 240 mA and the smart-key data shows an exterior handle request toggling with nobody near the car.
Should the low-voltage battery be replaced first, or can the wake input be proven?
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16/07/2026 9:11 am
Charge and test the low-voltage battery, but capture the draw and wake reason before replacing it. Move all keys away, monitor handle-request states and disconnect only the suspect low-voltage handle circuit according to the diagram. If current then completes its sleep sequence, the input is waking the vehicle.
Do not probe orange high-voltage connectors; this diagnosis is on the 12 V wake circuit. After repairing the cause, retest battery capacity because repeated deep discharge may have damaged it.
Topic starter
17/07/2026 10:19 am
The left-front exterior handle request flickered in wet conditions. Disconnecting that low-voltage handle allowed current to settle below 30 mA. Replacing the handle switch stopped the wake events; the tested 12 V battery recovered and no further reset was needed.