Circuit Description

WARNING: This page is about a different car, the 2002 Lexus RX 300. However, it is still accessible from the selected car via links, so may be relevant.

The ECT sensor is a thermistor that monitors coolant temperature. If DTC P0116 is set, ECM will operate in a fail-safe mode, in which engine coolant is assumed to be 176°F (80°C). Possible causes are:

Faulty ECT sensor.
Faulty cooling system.

NOTE: If DTCs P0115 and P0116 are output together, diagnose DTC P0115 first. Inspect engine coolant temperature circuit for an open. Repair as necessary. See WIRING DIAGRAMS article.