What it means
The ECM detects a circuit range/performance fault on the hybrid/ev battery temperature sensor b circuit. Reading cannot be used reliably for control.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Battery temperature sensor B monitors the temperature at one location in the hybrid/EV battery pack so the control module can manage battery operation. P0AC6 sets when the sensor's reported temperature or response falls outside the expected range or does not behave plausibly, even if the circuit is electrically connected.
Common causes
Most likely first.
- Sensor characteristic drifted
- Sensor mounting displaced
- Sensor element aged beyond calibration window
Symptoms
- EV/hybrid system warning light on
- Reduced power output or limp mode
- Charging may fail or be slowed
- Reduced electric range
How to diagnose it
- Save freeze-frame data and scan for companion battery-temperature codes to see when sensor B's reading became implausible.
- Compare sensor B live data with other battery temperature sensors and ambient or recent operating conditions; look for a consistent offset or a response that fails to change plausibly.
- Inspect sensor B's mounting and connector to confirm it is seated in its intended position and that its wiring is not strained or damaged.
- Check sensor B circuit continuity and connections against the manufacturer's wiring information to rule out an electrical fault affecting the reading.
- If mounting and wiring are sound, test sensor B's response against the manufacturer's procedure to determine whether it has drifted beyond calibration.
Common fixes
- Reseat battery temperature sensor B in its proper mounting position.
- Repair loose, damaged, or corroded sensor B wiring and connections.
- Replace sensor B if its temperature response fails the manufacturer's range/performance test.
- Repair a confirmed battery control module input fault.
Can I keep driving?
Avoid strenuous driving or charging if the vehicle limits power or displays a hybrid warning, because an inaccurate sensor B reading can lead the system to restrict battery use. Stop if an overheating warning appears.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.