Faulty coolant temperature sensor C, such as an open or shorted thermistor element; Damaged or corroded wiring harness between the sensor and the battery control module; Loose, backed-out, or water-intruded connector pins at the sensor or module; Coolant level low or air pockets causing the sensor to read incorrectly; Failed battery control module or hybrid control module internal driver circuit; Aftermarket or incorrect sensor installed during prior repairs

DTC codes / P2Dxx · Hybrid propulsion / P2D52

P2D52Hybrid/EV Battery Pack Coolant Temperature Sensor C Circuit

Q: What does code P2D52 mean?

Hybrid/EV Battery Pack Coolant Temperature Sensor C Circuit. P2D52 indicates that the hybrid or electric vehicle battery pack coolant temperature sensor circuit C is reporting a voltage or signal outside the expected range, so the battery control module cannot reliably monitor coolant temperature. The computer sets this code when the sensor signal is too high, too low, or intermittent for a calibrated period, which may trigger reduced power or charging limits to protect the battery.

P2D52 indicates that the hybrid or electric vehicle battery pack coolant temperature sensor circuit C is reporting a voltage or signal outside the expected range, so the battery control module cannot reliably monitor coolant temperature. The computer sets this code when the sensor signal is too high, too low, or intermittent for a calibrated period, which may trigger reduced power or charging limits to protect the battery.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaHybrid propulsion

Symptoms you may notice

Illumination of the hybrid system warning light or service vehicle soon message
Reduced electric driving range or forced engine running in plug-in hybrids
Limited power output or reduced charging rate, especially in hot or cold weather
Active grille shutters or coolant pump may run continuously or not at all
Often no symptoms besides the warning light, particularly in mild ambient temperatures

Common causes, most likely first

Faulty coolant temperature sensor C, such as an open or shorted thermistor element
Damaged or corroded wiring harness between the sensor and the battery control module
Loose, backed-out, or water-intruded connector pins at the sensor or module
Coolant level low or air pockets causing the sensor to read incorrectly
Failed battery control module or hybrid control module internal driver circuit
Aftermarket or incorrect sensor installed during prior repairs

How to diagnose and fix it

Verify coolant level and condition, then pressure-test the battery coolant loop for leaks or air pockets
Inspect the sensor connector and harness for corrosion, chafing, or loose pins, and perform a wiggle test while watching live data
Measure sensor resistance at known temperatures and compare with the manufacturer's resistance chart
Check reference voltage and ground at the sensor connector with a multimeter to rule out wiring faults
If wiring and sensor test good, substitute a known-good sensor and clear the code to see if it returns
Perform a battery control module software update if a calibration bulletin applies to the vehicle
Replace the sensor or repair the harness as needed, then clear codes and verify the coolant temperature reading matches ambient after a cold soak

Coolant sensor C faults that fool technicians

A low coolant level or trapped air in the battery pack coolant loop often sets this code because the sensor reads air temperature instead of liquid temperature, so always bleed the system before condemning the sensor.
The sensor C circuit may share a common ground or reference voltage with other temperature sensors, so a fault in a different sensor can pull the C circuit out of range and set this code without any problem in sensor C itself.
On many hybrids the battery coolant temperature sensor is part of a combined sensor block or harness that also includes the inlet and outlet sensors, and replacing only the C sensor may not be possible or may require replacing the entire assembly.
Intermittent codes that appear only after a cold start or during high-load driving often point to a harness chafe near a bracket or a connector that expands with heat, not a failed sensor.
A battery control module that has logged this code may keep the coolant pump running after shutdown or disable active grille shutters, which can drain the 12-volt battery and create a no-start condition that misleads diagnosis.

Can I keep driving with P2D52?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy acceleration, sustained high speeds, and fast charging because the battery may overheat without proper coolant temperature monitoring. If the hybrid system warning light flashes or power is severely limited, stop driving and have the vehicle 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.