What it means
The motor electronics coolant temperature sensor B reports a circuit low 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 sends a signal used to monitor power electronics coolant temperature. P2BDA sets when the control module sees Sensor B’s signal voltage lower than expected, which can result from a signal wire short to ground or an internally shorted sensor.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal sensor short
- Connector pins corroded - high contact resistance
Symptoms
- Hybrid-system warning light or message
- Reduced power
- Power electronics overheating warning
How to diagnose it
- Check freeze-frame data and related hybrid-system codes to see when Sensor B’s low-circuit fault occurred and what temperature the module reported.
- Inspect Sensor B’s connector and harness for corrosion, pin damage, or a signal wire rubbed through and contacting ground.
- Compare Sensor B’s scan-tool reading with other coolant temperature readings and ambient temperature to confirm whether the reported value is implausible.
- Test the Sensor B signal wire for a short to ground and check the connector terminals using the manufacturer's wiring diagram and specifications.
- If the wiring is sound, test Sensor B for an internal short using the manufacturer's procedure and replace it if it fails.
Common fixes
- Clean and secure corroded Sensor B connector pins.
- Repair the Sensor B signal wire where it is shorted to ground or damaged.
- Replace Sensor B if it has an internal short or fails the specified test.
Can I keep driving?
Stop safely if a power electronics overheating warning appears or power is reduced; unreliable Sensor B data can impair cooling control and overheating may damage the inverter or motor electronics. If no warning is present, minimize driving and arrange prompt diagnosis.
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.