P0C97
Hybrid/EV Battery Temperature Sensor L Circuit.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- C
- AreaHybrid propulsion
- 97
- FaultThe specific fault in that area
What it means
P0C97 means the hybrid or EV battery control unit has detected a fault in the circuit of battery temperature sensor 'L'. The reading was outside the expected range, implausible against neighbouring sensors, or the circuit was open or shorted. Which physical sensor 'L' refers to, and where it sits in the pack, depends on the vehicle and battery design.
Symptoms
- Hybrid or EV system warning light, or malfunction indicator lamp, on
- Reduced power or limp-home mode
- Reduced regenerative braking or charging performance
- Battery cooling fan running loudly or constantly
- Reduced electric-only range or the engine running more often on a hybrid
- Slower or interrupted charging
Possible causes
- Faulty battery temperature sensor 'L' (internal open or short, or drifted reading)likely
- Damaged, corroded or loose sensor connector or terminalslikely
- Open circuit, chafing or short in the sensor wiring or sensor harness inside the packpossible
- Blocked battery cooling duct or failing cooling fan causing a genuine temperature mismatchpossible
- Fault in the battery monitoring or control module's sensor input or reference supplyrare
- Moisture or coolant ingress affecting the sensor circuitrare
How to diagnose
- Read all stored and pending codes and the freeze frame data, noting battery temperatures, state of charge and whether other temperature or battery codes are present.
- Check for manufacturer technical bulletins and the service information for where sensor 'L' is located on this model.
- Inspect the battery cooling intake, ducts, filter and fan for blockage, debris or damage.
- With the car cold-soaked, compare live data from all battery temperature sensors with each other and with ambient temperature; look for one that is stuck, implausible or reading out of range.
- Have a technician trained in high-voltage systems isolate the system following the official procedure, then inspect the sensor connector and harness for corrosion, bent pins, chafing or moisture.
- Measure the sensor resistance and the circuit wiring resistance against the manufacturer's specification, and test for shorts to ground or supply.
- Check the reference voltage, ground and signal at the control module connector to confirm the module is supplying and reading the circuit correctly.
- After repair, clear the code and road test while watching live temperature data to confirm the sensor reads plausibly and the code does not return.
How to fix
- Repair or replace damaged wiring, terminals or connectors in the sensor circuit.
- Replace the faulty battery temperature sensor or the sensor harness assembly, as the model's design requires.
- Clear blocked cooling ducts and repair or replace a faulty battery cooling fan.
- Dry out and repair any moisture ingress, and fix the source of the leak.
- Replace or repair the battery control module only after the sensor and wiring have been proven good.
- Clear the code and complete a verification drive to confirm the repair.
Can I keep driving?
The car can usually be driven for a short time, but expect reduced power and possible limp mode, and the battery may not be protected properly if temperatures cannot be monitored. Get it checked soon by a technician trained in high-voltage systems, and stop driving if there is a burning smell, a high-temperature warning or a red warning message.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.