What is code p135 heat sensor circuit malfunction?

Code P135 indicates a malfunction in the heat sensor circuit, typically related to the engine's temperature sensor or its wiring. This issue can cause incorrect readings of the engine temperature, potentially leading to poor engine performance or increased emissions. It's important to diagnose and repair the underlying problem, which may involve checking the sensor itself, its connections, or the engine control unit (ECU). Addressing this code promptly can help maintain optimal engine function and prevent further complications.