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2018 Sorento EX V6: Persistent Battery Drain - What's drawing power?

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Emily N. · rep 0 · May 22, 3:09 AM · 1 replies · solved · Question

Vehicle: 2018 Kia Sorento EX V6

Hey everyone, I'm having a really frustrating issue with my 2018 Kia Sorento EX V6. For the past few weeks, if I leave it parked for more than a day, the battery is completely dead. I've replaced the battery twice, and the alternator was checked and seems fine.

I've tried to make sure everything is off when I leave the car, but it still happens. Could it be a module staying awake, or maybe something in the infotainment system? I'm not getting any warning lights on the dash when it's running, only the dead battery in the morning.

I'm at my wit's end trying to figure out what's causing this parasitic draw. Any ideas on common culprits for this model year or how I can diagnose it myself before taking it to the dealership?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:09 AM

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ClearTheCode admin answer:

Persistent battery drain, also known as a parasitic draw, can be tricky to diagnose but is a common issue. Here's how you can approach it and what might be causing it:

  1. Initial Checks:

    • Verify Battery & Alternator: Even if checked, ensure both are truly healthy. A weak battery can fail quickly, and a failing alternator might not always trigger a warning light immediately. Have a professional load test done on the battery and a full charging system test.
    • Check for Obvious Culprits: Ensure interior lights, glove box lights, trunk lights, and any aftermarket accessories (dash cams, chargers) are turning off completely.

  2. Diagnosing Parasitic Draw (DIY with Multimeter):

    • Connect Multimeter: Disconnect the negative battery terminal. Connect a multimeter in series between the negative battery post and the disconnected negative battery cable, set to measure amperage (A or mA). The initial draw will be high; wait about 15-30 minutes for all modules to 'go to sleep'. A normal draw is typically under 50mA.
    • Pull Fuses: Systematically pull one fuse at a time from both the under-hood and interior fuse boxes. Watch the multimeter reading. When the amperage drops significantly, you've identified the circuit causing the draw. This narrows down the problem area.

  3. Common Causes for Kia Sorento:

    • Infotainment System: Head units, especially with navigation, can sometimes fail to power down correctly.
    • Body Control Module (BCM): A faulty BCM can keep various systems active.
    • Relays: A stuck relay (e.g., for the cooling fan, fuel pump, or accessory power) can continuously draw power.
    • Door/Trunk Latches: Faulty switches in door or trunk latches can make the car think a door is ajar, keeping interior lights or modules awake.
    • Aftermarket Accessories: Improperly wired aftermarket alarms, stereos, or remote start systems are frequent culprits.

  4. When to See a Shop:

    • If you're uncomfortable performing the multimeter test or can't pinpoint the circuit, it's best to visit a qualified technician. They have specialized diagnostic tools (like scan tools that can monitor module sleep states) and experience to quickly identify the source of the draw. They can also check for specific Diagnostic Trouble Codes (DTCs) related to module communication or power management, although a parasitic draw itself might not always trigger a specific OBD-II code directly unless it causes a low voltage condition that affects other systems (e.g., P0562 - System Voltage Low).
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