Circuit Description

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

The IAT sensor is a thermistor built into the MAF sensor to monitor temperature of air flowing through MAF sensor. Based on IAT sensor signal, ECM increases fuel injection volume to improve driveability during cold engine operation. If DTC P0110 is set, ECM will operate in fail-safe mode, in which intake air temperature is assumed to be 68°F (20°C). DTC P0110 is set when ECM detects an open or short in IAT sensor circuit. Possible causes are:

Open or short in IAT sensor circuit.
Faulty IAT sensor.
Faulty ECM.

NOTE: If DTCs P0110, P0115 and P0120 are output together, inspect ECM terminal E2 (ground) circuit for an open. Repair as necessary. See WIRING DIAGRAMS article.