Yes, based on your description, it does sound likely that a faulty sensor is causing the issue — most likely the coolant temperature sensor (CTS).
Here’s why:
A bad CTS can send incorrect signals to the ECU, making the engine think it’s colder (or hotter) than it really is.
If the ECU believes the engine is cold, it may increase the revs to help "warm up," even if not needed.
The temperature warning light at cold start could be due to an erratic reading from this sensor, which then stabilizes after a few minutes.
Your coolant levels and heating system seem fine, which rules out serious coolant circulation problems.
Other possibilities:
Thermostat stuck open or slow to close (less likely, as your heater warms up properly).
Idle Air Control Valve (IACV) issue — but this wouldn’t explain the warning light.
A loose or corroded connection to the CTS.
Recommended next step:
Have the coolant temperature sensor tested or replaced (they’re relatively inexpensive) and check the wiring/connectors going to it.
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JK Repair Hybrid Batteries they will guide you better.
