What it means
The motor electronics coolant temperature sensor B reports a circuit condition. Power electronics cooling cannot be regulated reliably.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Motor electronics coolant temperature sensor B measures coolant temperature at its location in the power electronics cooling system. The control module monitors Sensor B’s electrical signal and sets P2BD8 when it detects a circuit fault that prevents it from reliably reading that signal.
Common causes
Most likely first.
- Sensor failed
- Wiring or connector fault
Symptoms
- Hybrid-system warning light or message
- Reduced power
- Power electronics overheating warning
How to diagnose it
- Read freeze-frame data and related hybrid-system codes to identify the conditions when Sensor B’s circuit fault appeared and whether temperature readings became implausible.
- Locate Sensor B using the manufacturer's service information and inspect its connector and wiring for corrosion, loose pins, chafing, or damage.
- Compare Sensor B’s scan-tool temperature reading with other available coolant temperature readings and the vehicle’s cold-soak temperature to spot an obviously invalid signal.
- Check the Sensor B circuit, connector terminals, and sensor using the manufacturer's wiring diagram and electrical specifications.
- If the harness and connections test correctly, test Sensor B against the manufacturer's specification and replace it if it fails.
Common fixes
- Clean and secure Sensor B’s corroded or loose connector pins.
- Repair damaged wiring or connector terminals in the Sensor B circuit.
- Replace Sensor B if it fails the manufacturer's electrical test.
Can I keep driving?
If a power electronics overheating warning or reduced power occurs, stop safely and avoid further driving because cooling control may be unreliable. Without those symptoms, drive only as needed for prompt diagnosis and watch for temperature or hybrid-system warnings.
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.