P0516
Universal (All Makes) Vehicle (OBD-II)
Severity: MinorWhat Does This Error Mean?
P0516 means the battery temperature sensor circuit is reading lower than its valid range. For an NTC thermistor (the type used for battery temperature sensors), a low-voltage signal means the sensor is reading an unrealistically high temperature — or the circuit has a short to ground. In practical terms: the PCM thinks the battery is extremely hot when it probably is not. This can cause the PCM to reduce charging voltage unnecessarily, leading to an undercharged battery.
Affected Models
- Vehicles 2000 and newer with intelligent charging voltage management
- Common on GM, Ford, Chrysler, and Ram vehicles
- European vehicles with battery management systems (BMW, Mercedes, Audi, VW)
- Hybrid vehicles with battery thermal monitoring for the 12V auxiliary battery
- Any vehicle where the PCM continuously monitors battery temperature sensor voltage
Common Causes
- Battery temperature sensor has an internal short, pulling the signal voltage to ground
- Sensor wiring is shorted to ground — wiring chafed against chassis or battery tray metal
- Connector on the sensor has a grounded pin or internal short due to corrosion or moisture
- Sensor has been physically damaged, crushing the internal thermistor element
- PCM reference voltage circuit has an issue dropping the sensor supply below its normal 5V reference
How to Fix It
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Unplug the battery temperature sensor connector. Use a multimeter to measure resistance between the signal wire and chassis ground. If you read near zero ohms, the wiring has a short to ground between the sensor and the PCM.
Resistance to ground should be very high (hundreds of thousands of ohms) on a PCM reference/signal circuit when the sensor is disconnected.
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Measure resistance across the sensor terminals themselves. If the sensor reads near zero ohms, it has an internal short and needs replacement.
An NTC thermistor should never read near zero — that is not a real temperature, it is a failed component.
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Inspect the sensor and its wiring visually for any physical damage. Look for the sensor body being crushed or cracked, which can cause the internal element to short. This can happen if the battery was recently replaced and the sensor was inadvertently sat on or pinched.
Battery temperature sensors are small and easy to damage during battery replacement — always confirm the sensor is intact and properly remounted after any battery service.
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Trace the wiring harness from the sensor to the PCM/BCM looking for any spots where insulation has worn through against metal. Common areas include the battery tray edges, wiring bundle routing clips, and any area near the exhaust or heat sources.
Heat-damaged insulation on battery area wiring can be identified by stiff, cracked, or discolored sections of wire.
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Replace the sensor and repair any wiring damage found. Perform a BMS reset using a scan tool if required by your vehicle. Verify the sensor reading after replacement — it should match ambient temperature approximately.
If the repaired wiring later causes the code to return, a more complete harness section replacement may be needed.
When to Call a Professional
A shorted sensor is cheap to replace. If the wiring is shorted to ground, finding the fault requires a wiring schematic and patience. A shop can diagnose and repair P0516 in under 2 hours in most cases.
Frequently Asked Questions
What happens to charging if the PCM thinks the battery is very hot?
The PCM reduces charging voltage when it believes the battery is hot. If the sensor is erroneously reading a very high temperature, the PCM will drop charging voltage too low. This leaves the battery chronically undercharged, which causes sulfation, reduced capacity, and eventually a dead battery.
Can the battery itself cause P0516?
Not directly — P0516 is a sensor circuit fault, not a battery health code. However, if acid from the battery has damaged the nearby wiring, the battery is indirectly responsible. Inspect the battery for any case damage or acid leaks if P0516 appears alongside other unexplained electrical faults.
How do I know if the BMS reset is required after repair?
Check your service manual or ask the parts supplier when you buy the sensor. Vehicles with an active Battery Monitoring System (GM, Ford, European models) typically require the reset. Vehicles with a simpler temperature-compensated charging system may not require it. When in doubt, have a shop perform the reset — it only takes a few minutes.