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P0517Battery Temperature Sensor Circuit High

The battery temperature sensor signal voltage is higher than the normal operating range.

Definition

The battery temperature sensor is a thermistor the PCM reads to adjust alternator charging voltage for battery temperature. P0517 sets when the signal voltage rises above the plausible maximum, which usually means the circuit is open — a broken wire, disconnected sensor, or failed-open element — and falsely reports an extremely cold battery. The PCM reverts to a default charging voltage, so the practical symptoms are a warning lamp and possible long-term overcharging that shortens battery life or causes electrolyte loss.

Common causes

  • Open or failed battery temperature sensor element
  • Broken or corroded-open wiring under the battery tray
  • Disconnected or backed-out connector terminal
  • Open sensor ground circuit
  • PCM input fault (rare)

Common misdiagnoses

  • Alternator
  • Battery
  • Voltage regulator
  • PCM

Troubleshooting steps

  1. 1.Read the battery temperature PID

    A reading pegged at the extreme cold value (often -40 degrees) regardless of actual conditions confirms an open signal circuit.

  2. 2.Jumper the sensor connector

    Unplug the sensor and bridge the two connector terminals with a fused jumper; if the reading swings fully hot, the harness and PCM are good and the sensor is open.

  3. 3.Inspect the connector and pigtail

    Check for backed-out or acid-corroded terminals at the sensor connector, the most common failure point beneath the battery.

  4. 4.Trace the open circuit

    If jumpering does not change the reading, measure continuity of the signal and ground wires to the PCM connector to find the break.

  5. 5.Repair and verify

    Replace the sensor or repair the open wire, then confirm the temperature reading tracks ambient and charging voltage responds normally.

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