P0515
Battery Temperature Sensor Circuit.
- Generic
- Powertrain
- Generic code
- Low severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 5
- AreaVehicle speed, idle control and auxiliary inputs
- 15
- FaultThe specific fault in that area
What it means
P0515 is the generic SAE J2012 code for a fault in the battery temperature sensor circuit. The control unit uses this sensor to adjust charging voltage to suit battery temperature. It sets the code when the sensor signal is out of range, implausible, or does not agree with other temperature data such as engine coolant or intake air temperature after a cold soak. Sensor location and how the strategy works vary by vehicle, so check the model-specific information.
Symptoms
- Engine management warning light on
- Battery or charging warning light on in some cases
- Battery undercharged or slow cranking, especially in cold weather
- Battery overcharged or electrolyte loss in hot conditions
- Stop-start system disabled or behaving erratically
- Fluctuating or incorrect charging voltage
Possible causes
- Damaged, corroded or loose wiring or connector at the battery temperature sensorlikely
- Faulty battery temperature sensor (open or short circuit, or drifted resistance)likely
- Sensor integrated into a battery monitoring module or intelligent battery sensor that has failedpossible
- Poor battery terminal connections or corrosion affecting the sensor or monitoring unitpossible
- Wiring fault between the sensor and the control unit (short to earth, short to voltage or open circuit)possible
- Fault in the control unit that reads the sensor, or outdated software where the manufacturer has issued a fixrare
How to diagnose
- Read the stored codes and freeze frame data, and note whether the fault is current or intermittent, plus any other charging or battery codes.
- Visually inspect the battery, terminals, sensor and its wiring for corrosion, chafing, heat damage and loose connectors.
- Check the battery condition and charging system output with a load test and charging voltage measurement, as a poor battery can cause related symptoms.
- Compare the live battery temperature reading with ambient or other temperature data after the car has cold soaked; they should be similar.
- Check the sensor resistance or signal against the manufacturer specification for the temperature, as the values depend on the model.
- Test the wiring for continuity, short to earth and short to voltage, and check the reference and earth supply at the sensor connector.
- Check for technical service bulletins or software updates relevant to the vehicle before replacing the control unit.
How to fix
- Repair or replace damaged wiring and clean or replace corroded connectors.
- Replace the battery temperature sensor, or the battery monitoring module if the sensor is part of it, following the manufacturer procedure.
- Clean and tighten battery terminals and earth connections, and replace the battery if it is failing.
- Repair the circuit wiring fault found between the sensor and control unit.
- Update the control unit software if a manufacturer update addresses the fault, and only replace the unit once all else is ruled out.
Can I keep driving?
The car can usually be driven for now, but book it in soon because incorrect charging control can leave the battery undercharged or overcharged over time. Avoid relying on the car for long trips or in very cold weather until the fault is fixed.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.