What it means
The signals of the hybrid electronics 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 hybrid electronics cooling loop uses temperature sensors A and B to report coolant temperature to the control module. The module compares their readings, and sets P2D2A when the two readings disagree beyond the allowed range, such as from sensor drift or swapped channel connections.
Common causes
Most likely first.
- One sensor characteristic drifted
- Harness incorrectly swapped between channels
Symptoms
- Check-engine or hybrid-system warning
- Power limited warning
- Reduced performance under load
How to diagnose it
- Use a scan tool to record freeze-frame data and compare live readings from electronics coolant sensors A and B, noting whether the mismatch appears cold, warm, or throughout operation.
- With the vehicle safely powered down according to its high-voltage shutdown procedure, inspect both sensor connectors and harness routing for damage, loose plugs, or evidence that the A and B channels were crossed.
- Compare each sensor reading with the actual coolant temperature and with the other sensor during a cold soak, when both should be close to the same temperature.
- Check each sensor circuit and connector for continuity, shorts, or poor terminal contact using the vehicle wiring diagram and manufacturer's test specifications.
- If wiring and connections are sound, test the sensors individually against the manufacturer's specification to identify a drifting sensor.
Common fixes
- Reconnect loose sensor plugs and repair damaged wiring or terminals.
- Correct crossed A and B harness connections.
- Replace the electronics coolant temperature sensor that fails its specification.
- Clear the code and confirm the two readings track consistently through a cold start and warm-up.
Can I keep driving?
Avoid heavy acceleration or sustained high loads if a hybrid-system or power-limited warning appears, because inaccurate temperature readings can cause the system to restrict output or protect components. Arrange diagnosis promptly, especially if the warning persists.
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.