What it means
The hybrid/EV battery pack coolant temperature sensor D circuit signal is intermittent or erratic, so the temperature reading may be unreliable.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Sensor D measures coolant temperature in the hybrid or EV battery pack cooling system. The control module monitors whether its signal remains stable; this code sets when the reading jumps, drops out, or otherwise varies erratically, making pack temperature control less reliable.
Common causes
Most likely first.
- Sensor connector not seated
- Noisy ground reference
- Connector with intermittent contact under vibration
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 watch Sensor D live data for dropouts or sudden jumps, especially when the warning occurs.
- With the vehicle safely powered down according to its service instructions, check that Sensor D's connector is fully seated and its lock is intact.
- Inspect accessible Sensor D wiring and ground-reference connections for chafing, looseness, corrosion, or signs of vibration-related movement.
- If permitted by the manufacturer's service procedure, monitor Sensor D data while gently moving the accessible harness to look for an intermittent change.
- Test the Sensor D ground reference, connector contact, and wiring continuity against the manufacturer's specification before condemning the sensor.
Common fixes
- Reseat and secure Sensor D's connector.
- Clean or repair loose, corroded, or damaged connector and ground-reference connections.
- Repair wiring that loses contact under vibration.
- Replace Sensor D if its output remains erratic with verified wiring and connections.
Can I keep driving?
Power and charging may be limited if the vehicle cannot trust the battery coolant temperature reading. Avoid hard acceleration and stop if a battery-temperature or overheating warning appears.
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.