P0515Battery Temperature Sensor Circuit
There is a general malfunction in the battery temperature sensor circuit.
Definition
The battery temperature sensor lets the PCM adjust alternator output voltage to match battery temperature, protecting the battery from overcharging when hot and undercharging when cold. P0515 sets when the PCM detects a fault in the sensor circuit that it cannot classify simply as low or high — such as erratic readings or an implausible signal. The PCM substitutes a default charging voltage, so the only symptoms are often a stored code and, over time, reduced battery life; some applications illuminate the battery or check engine lamp.
Common causes
- Failed battery temperature sensor
- Corroded connector terminals from battery acid or moisture
- Open, shorted, or chafed sensor wiring
- Poor sensor ground circuit
- Damaged battery tray dislodging the sensor
- PCM input fault (rare)
Common misdiagnoses
- Alternator
- Battery
- Voltage regulator
- PCM
Troubleshooting steps
1.View the sensor reading on a scan tool
Check the battery temperature PID; a reading pegged at the extreme cold or hot limit, or one jumping erratically, confirms a circuit problem.
2.Inspect the sensor location
The sensor typically mounts in the battery tray; remove the battery and check for acid corrosion on the sensor, connector, and pigtail.
3.Test the sensor resistance
Disconnect the sensor and compare its resistance to the manufacturer's temperature chart; an open or shorted element means a failed sensor.
4.Check the circuit to the PCM
Verify the signal and ground wires each show under 1 ohm to the PCM connector and no shorts to power or ground.
5.Repair and confirm charging behavior
After replacing the sensor or repairing wiring, verify the temperature reading is plausible and charging voltage responds normally.