What Does P0C84 Mean?
DTC P0C84 indicates that the hybrid battery temperature sensor H circuit voltage is above the maximum valid threshold. For NTC thermistor circuits, high voltage indicates either an extremely low temperature reading or an open circuit. The BMS has determined that the sensor H signal has exceeded its valid electrical range, most commonly due to a disconnected or failed-open sensor.
Common Causes
30%
Open circuit in the sensor H wiring harness (broken wire, pulled connector)
25%
Open-circuit NTC thermistor failure at sensor H
20%
Corroded or backed-out connector pins at sensor H causing open connection
15%
Short to voltage supply in the sensor H signal wire
10%
BMS input circuit fault on the sensor H channel
Diagnostic Steps
1
Measure voltage at the sensor H signal pin at the BMS connector to confirm it exceeds the valid range.
2
Disconnect sensor H and measure thermistor resistance; infinite (open-loop) resistance confirms a failed-open sensor.
3
Substitute a known-good resistance value at the BMS connector to verify the BMS reads correctly, isolating the fault.
4
Test wiring continuity from the BMS connector to the sensor H connector, checking for opens and shorts to power.
5
Inspect connector pins for corrosion, physical damage, or backing out that causes an intermittent or permanent open.
Estimated Repair Cost
$100 - $600
Parts + labor, varies by vehicle and location
DTC P0C84 indicates that the hybrid battery temperature sensor H circuit voltage is above the maximum valid threshold. For NTC thermistor circuits, high voltage indicates either an extremely low temperature reading or an open circuit. The BMS has determined that the sensor H signal has exceeded its ...
The most common cause of P0C84 (Hybrid Battery Temperature Sensor "H" Circuit High) is: Open circuit in the sensor H wiring harness (broken wire, pulled connector)
Typical repair costs for P0C84 range from $100 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A high circuit reading may be interpreted as extremely cold battery temperature, which could allow the BMS to permit charging or discharging rates that are unsafe for the actual battery temperature. Sensor defaulting removes monitoring coverage for that zone.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0C84 to identify the root cause.
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Quick Info
Category
Powertrain
System
Hybrid Battery Thermal Management
Difficulty
Type
Generic (SAE)
Recommended Tools
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