Open circuit or high resistance in the sensor J signal wire, often due to a broken wire or corroded connector; Short to voltage on the sensor J signal circuit, such as chafed insulation contacting a power wire; Failed temperature sensor J internal to the battery pack, reading out of range; Poor terminal tension or water intrusion at the battery pack connector; Faulty battery energy control module or hybrid control module not processing the signal correctly; Damaged wire harness from rodent damage or previous service work near the pack

DTC codes / P0Cxx · Hybrid propulsion / P0C90

P0C90Hybrid/EV Battery Temperature Sensor J Circuit High

Q: What does code P0C90 mean?

Hybrid/EV Battery Temperature Sensor J Circuit High. P0C90 indicates that the hybrid or electric vehicle battery pack's temperature sensor J circuit is reporting a voltage higher than the manufacturer's expected range, which the battery energy control module interprets as an open circuit or a short to voltage. The computer sets this code when the sensor signal line exceeds the calibrated maximum for a set time, typically indicating a wiring fault, a failed sensor, or a poor connection rather than an actual overheating event.

P0C90 indicates that the hybrid or electric vehicle battery pack's temperature sensor J circuit is reporting a voltage higher than the manufacturer's expected range, which the battery energy control module interprets as an open circuit or a short to voltage. The computer sets this code when the sensor signal line exceeds the calibrated maximum for a set time, typically indicating a wiring fault, a failed sensor, or a poor connection rather than an actual overheating event.

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
Often no symptoms besides the warning light, especially if the fault is intermittent
Reduced electric-only range or forced engine operation in hybrids due to limited battery power
Battery cooling fan may run continuously or not at all if the module loses valid temperature data
Possible derating of charging rate or propulsion power to protect the battery pack
In rare cases, a no-start condition if the module cannot confirm safe battery temperature

Common causes, most likely first

Open circuit or high resistance in the sensor J signal wire, often due to a broken wire or corroded connector
Short to voltage on the sensor J signal circuit, such as chafed insulation contacting a power wire
Failed temperature sensor J internal to the battery pack, reading out of range
Poor terminal tension or water intrusion at the battery pack connector
Faulty battery energy control module or hybrid control module not processing the signal correctly
Damaged wire harness from rodent damage or previous service work near the pack

How to diagnose and fix it

Scan all modules for related codes and record freeze-frame data to see when the fault occurred
Inspect the battery pack connectors and sensor J harness for corrosion, water intrusion, or loose terminals
Measure resistance of sensor J at the module connector and compare to the manufacturer's temperature-resistance chart
Check for short to voltage on the signal circuit by measuring voltage with the sensor disconnected and key on
Perform a wiggle test on the harness while monitoring sensor J voltage to catch intermittent opens
If wiring and connectors are good, replace the temperature sensor J or the sensor assembly per service information
Clear codes and verify the sensor J voltage reads within normal range across a full drive cycle

What a high sensor J circuit really means

A high voltage on a temperature sensor circuit almost always means an open circuit or a short to voltage, not that the battery is actually hot, so do not replace the pack based on this code alone.
The sensor J circuit often shares a common ground with other temperature sensors, so a bad ground can set multiple temperature sensor codes at once and mislead you into replacing good sensors.
Intermittent P0C90 is frequently caused by a pin fit issue or water in a connector that only acts up in damp weather or over bumps, so a static resistance check may pass.
Some vehicles set this code when the battery pack cooling fan fails and the module sees an unrealistic temperature spread, so check cooling system operation before condemning the sensor.
After repairs, the code may remain stored until the module sees a valid sensor J voltage through a complete ignition cycle, so do not assume the fix failed if the light stays on immediately.

Can I keep driving with P0C90?

You can usually drive the vehicle with this code, but avoid aggressive acceleration, fast charging, or long trips until it is repaired because the module may not be able to protect the battery from overheating. If the hybrid system warning light is flashing or the vehicle enters a reduced power mode, have it checked promptly.

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.