The Problem
2024 Kia EV9 RWD Long Range (14,700 miles) brought in with DC fast charging capped at 50kW instead of rated 240kW. No warning on the cluster during normal driving. Fault appeared after the first winter season. P0D16 (Battery Temperature Sensor Circuit Low) confirmed via GDS2.
Diagnostic Procedure
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1. Confirm P0D16. BMS using fallback temperature value for charging rate calculation, limiting to conservative 50kW to protect pack.
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2. Check all battery temperature sensor readings in live data. Sensor 3 (rear left of pack) reads -40°C — physically impossible at 12°C ambient. Open circuit or shorted to ground on that sensor.
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3. Locate sensor 3 connector. Routes along rear undercarriage of battery pack. Remove underbody cover for access.
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4. Connector pin inspection — fine white powdery corrosion visible on pin 2 (signal low). Consistent with water intrusion followed by drying cycles. Vehicle has been pressure washed monthly since purchase.
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5. Clean connector pins with electrical contact cleaner. Apply dielectric grease. Reconnect.
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6. Sensor 3 now reads 13°C — matches ambient and other sensors.
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7. Clear P0D16. Initiate DC fast charge session. Charge rate climbs to 236kW at 20% SOC — within spec.
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8. No fault return after two weeks of monitoring (customer report).
Resolution & Root Cause
Battery temperature sensor connector cleaned and protected. Sensor reads correctly, full DC fast charge speed restored.
💡 Key Lesson
P0D16 on Kia EV9 with DC fast charge speed limited but no cluster warning is a sensor connector issue until proven otherwise. The battery temperature sensor connectors on the undercarriage are exposed to water intrusion from pressure washing or deep snow driving. A -40°C reading on a single sensor = open circuit. Clean the connector before condemning the sensor or BMS.
About This Case
This case was solved remotely by an HVDesk specialist with 15+ years of hands-on experience across major EV platforms including Tesla, Hyundai/Kia, Volkswagen ID series, BMW i-series, and Ford EVs. The procedure was provided as structured remote support to an independent auto repair shop.
