What it means
The BMS detects that battery pack subsection B is operating above the safe temperature threshold. Cell-level cooling or pack thermal management is compromised on this section.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The battery management system monitors temperature in hybrid/EV battery pack subsection B and compares it with the pack's safe operating limit. P2D46 sets when subsection B is too hot, which may result from reduced cooling flow to that section, local heating associated with cell imbalance, or resistance at a ground point.
Common causes
Most likely first.
- Coolant flow to this section reduced
- Cell imbalance causes local heating
- Ground point with elevated resistance
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
- Record freeze-frame data and compare subsection B temperature with other pack sections, battery load, and cooling commands.
- Check whether the temperature rise is localized to subsection B or follows heavy driving or charging.
- Inspect accessible cooling paths, hoses, and connections serving subsection B for leaks, blockage, or loose connections, observing high-voltage safety procedures.
- Review scan-tool cell voltage and temperature data for imbalance or a sensor reading that differs from neighboring sections.
- Have the subsection B ground path and battery thermal management tested to the manufacturer's procedure if the visible checks do not explain the temperature.
Common fixes
- Clear a confirmed blockage or restore coolant flow to subsection B.
- Repair a leak or damaged cooling connection serving subsection B.
- Repair a high-resistance ground connection after confirming it is the cause.
- Service the battery pack if cell imbalance or a failed temperature sensor is confirmed.
Can I keep driving?
Avoid driving and charging if the vehicle reports a battery over-temperature warning; stop safely and follow the vehicle's instructions. Continued heat in subsection B can cause severe power limitation and damage the high-voltage battery.
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.