Faulty battery pack coolant temperature sensor A; Damaged or corroded wiring harness or connector at the sensor; Short to ground in the sensor signal circuit; Poor electrical connection at the battery energy control module; Internal failure in the battery energy control module; Coolant contamination or sludge interfering with sensor operation; Aftermarket accessories or improper previous repairs disturbing the circuit

DTC codes / P0Cxx · Hybrid propulsion / P0C44

P0C44Hybrid/EV Battery Pack Coolant Temperature Sensor A Circuit Low

P0C44 indicates that the hybrid or electric vehicle battery pack coolant temperature sensor A circuit is reporting a voltage lower than the manufacturer's expected range. The battery energy control module monitors this sensor to protect the high-voltage battery from overheating or overcooling, and it sets this code when the signal stays below the low threshold for a calibrated time.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaHybrid propulsion

Symptoms you may notice

Illumination of the check engine light or service vehicle soon message
Often no symptoms besides the warning light
Reduced hybrid system power or forced limp mode in some vehicles
Battery cooling fan may run continuously or not at all
In rare cases, a noticeable decrease in electric-only range or charging performance
Possible overheating warning if the sensor is stuck low and the system cannot regulate temperature

Common causes, most likely first

Faulty battery pack coolant temperature sensor A
Damaged or corroded wiring harness or connector at the sensor
Short to ground in the sensor signal circuit
Poor electrical connection at the battery energy control module
Internal failure in the battery energy control module
Coolant contamination or sludge interfering with sensor operation
Aftermarket accessories or improper previous repairs disturbing the circuit

How to diagnose and fix it

Scan all modules and record freeze-frame data for P0C44 and any related codes
Visually inspect the sensor, connector, and wiring for damage, corrosion, or loose pins
Measure sensor resistance and compare to the manufacturer's temperature-resistance chart
Backprobe the sensor signal circuit to check for a short to ground with the sensor disconnected
Check continuity and voltage drop on the signal and ground circuits from the sensor to the control module
If wiring and sensor test good, perform a module reset and recheck; replace the control module only after confirming all other possibilities
Clear codes and verify the repair by running the vehicle through a complete drive cycle with battery cooling active

Coolant sensor faults that mimic other failures

A shorted sensor can make the control module believe the battery is colder than it is, causing the cooling fan to run constantly and mask an actual overheating condition.
Corrosion inside the connector often goes unnoticed because the outside looks clean, so always separate the connector and inspect the terminals under good light.
The code can set intermittently from vibration or water intrusion, so a wiggle test of the harness while watching live data is more reliable than a static resistance check alone.
Some vehicles use the same sensor signal for both cooling control and battery state-of-health calculations, so a low reading can also trigger unrelated hybrid system codes.
Replacing the sensor without checking the ground circuit is a common misdiagnosis, because a bad ground can pull the signal voltage low just like a failed sensor.

Can I keep driving with P0C44?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy acceleration, long highway trips, or fast charging because the battery cooling system may not regulate temperature correctly. If the vehicle enters limp mode or shows a high-voltage battery warning, stop driving and have it towed.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.