Faulty battery temperature sensor I or its internal connector; Damaged or chafed wiring harness between the sensor and the battery control module; Corroded or loose electrical connector pins at the sensor or module; Intermittent open or short in the sensor circuit due to vibration or heat cycling; Failed battery energy control module or hybrid control module; Software calibration issue in the battery management system

DTC codes / P0Cxx · Hybrid propulsion / P0C8C

P0C8CHybrid/EV Battery Temperature Sensor I Circuit Intermittent/Erratic

P0C8C indicates that the hybrid or electric vehicle battery temperature sensor circuit, specifically sensor I, is sending an intermittent or erratic signal to the battery energy control module. The computer monitors the sensor's voltage or resistance and flags this code when the reading jumps, drops out, or behaves inconsistently beyond a calibrated threshold.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaHybrid propulsion

Symptoms you may notice

Illumination of the hybrid system warning light or service vehicle soon message
Reduced electric-only range or forced engine operation in a hybrid
Inconsistent battery cooling fan operation or no fan activation
Sudden loss of power or reduced acceleration under load
Often no symptoms besides the warning light, especially in early stages

Common causes, most likely first

Faulty battery temperature sensor I or its internal connector
Damaged or chafed wiring harness between the sensor and the battery control module
Corroded or loose electrical connector pins at the sensor or module
Intermittent open or short in the sensor circuit due to vibration or heat cycling
Failed battery energy control module or hybrid control module
Software calibration issue in the battery management system

How to diagnose and fix it

Inspect the sensor connector and wiring for corrosion, looseness, or physical damage
Measure the sensor's resistance or voltage with a multimeter and compare to specifications
Perform a wiggle test on the harness while monitoring live sensor data to catch intermittent faults
Check for technical service bulletins or software updates for the battery control module
Replace the faulty temperature sensor if resistance is out of range or erratic
Repair or replace damaged sections of the wiring harness
If all else fails, diagnose or replace the battery energy control module

Intermittent faults hide in plain sight

A sensor that tests fine when cold can fail only after the battery pack reaches operating temperature, so always test both cold and hot.
The code can be set by a poor connection at the battery module connector rather than a failed sensor, so inspect terminals before condemning parts.
Some vehicles use a single sensor shared across multiple battery modules, and a fault in one module's wiring can mimic a sensor failure.
High-voltage battery cooling system faults, such as a failing fan, can cause temperature readings to swing and set this code indirectly.
After repairs, the code may require a drive cycle or a battery module relearn procedure to clear from memory.

Can I keep driving with P0C8C?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy acceleration, long trips, or extreme temperatures because an erratic temperature reading can lead to improper battery cooling or charging. If the hybrid system warning light flashes or power is severely reduced, stop driving and seek professional service.

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.