What it means
The signals of the HV battery pack coolant temperature sensors A and B do not correlate within the calibrated tolerance. One sensor drifts or installation offset between channels.
At a glance
- Usually lights the check-engine light
How it works
The battery pack cooling system uses temperature sensors A and B to help the control module manage battery temperature during driving and charging. P2D2B sets when the two sensor readings differ beyond the allowed correlation range; a drifting sensor, crossed channels, or an actual battery condition can contribute to the mismatch.
Common causes
Most likely first.
- One sensor characteristic drifted
- Harness incorrectly swapped between channels
- Pack cell imbalance approaching service threshold
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
- Use a scan tool to capture freeze-frame data and compare live battery pack coolant sensor A and B readings, along with any available battery temperature and cell-balance data.
- Inspect the battery cooling circuit sensor connectors and harness routing for damage, loose connections, or A/B channel crossover, following the vehicle's high-voltage safety procedure.
- After the vehicle has sat long enough for temperatures to settle, compare both readings with each other and with ambient conditions to identify an implausible offset.
- Check the A and B sensor circuits for open circuits, shorts, or poor terminal contact using the wiring diagram and manufacturer's specifications.
- If the circuits are sound, test each sensor against the manufacturer's specification and review battery cell-balance data for a related pack concern.
Common fixes
- Secure loose connectors and repair damaged sensor wiring.
- Correct crossed A and B harness connections.
- Replace the battery coolant temperature sensor that fails its specification.
- Address any confirmed battery cell imbalance or pack cooling fault using the vehicle's approved service procedure.
- Clear the code and verify that both readings remain correlated during charging and operation.
Can I keep driving?
Limit driving and avoid demanding acceleration or charging if power is reduced, charging is inhibited, or a hybrid-system warning is displayed. Continued operation with unreliable pack temperature information or a battery imbalance can lead to further power limits or charging restrictions.
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.