What Does P0BC4 Mean?
The hybrid battery temperature sensor "E" circuit is reading below the minimum expected voltage threshold. For a typical NTC thermistor circuit, a low voltage reading usually corresponds to an abnormally high resistance, which could indicate an open circuit, a disconnected sensor, or an extremely cold (implausible) temperature reading.
Common Causes
35%
Open circuit in the sensor E wiring (broken wire or disconnected connector)
25%
Failed NTC thermistor with internal open circuit
20%
Corroded connector pins creating high resistance exceeding sensor range
12%
BMS pull-up/pull-down resistor failure on the sensor E input
8%
Incorrect sensor type installed during previous service
Diagnostic Steps
1
Check the scan tool for the actual temperature value being reported by sensor E — an extremely low or default/impossible value confirms the circuit low condition.
2
Measure voltage at the sensor E connector with the sensor disconnected and compare to the expected reference voltage from the BMS pull-up circuit.
3
Test continuity of both wires from the sensor connector back to the BMS module — an open in either wire can cause a low voltage reading.
4
Measure sensor E resistance and verify it falls within the expected range for the current ambient temperature.
5
Inspect the connector at the BMS module for pushed-back or corroded pins on the sensor E channel.
Estimated Repair Cost
$100 - $600
Parts + labor, varies by vehicle and location
The hybrid battery temperature sensor "E" circuit is reading below the minimum expected voltage threshold. For a typical NTC thermistor circuit, a low voltage reading usually corresponds to an abnormally high resistance, which could indicate an open circuit, a disconnected sensor, or an extremely co...
The most common cause of P0BC4 (Hybrid Battery Temperature Sensor "E" Circuit Low) is: Open circuit in the sensor E wiring (broken wire or disconnected connector)
Typical repair costs for P0BC4 range from $100 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The BMS loses temperature monitoring for this battery zone. Depending on the vehicle's failure strategy, it may assume worst-case temperatures and derate the system, or it may continue operating without data from this zone, creating a blind spot for thermal protection.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0BC4 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Hybrid/EV Battery Thermal Management
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
