DTC C123 GMC
IAT Sensor Circuit High Input
IAT Sensor Circuit High Input
Description
DTC P0116-P0118, P0125, P0128, P0502 and P0503 not set, engine started, engine runtime over 180 seconds, ECT sensor more than 140ºF, MAF sensor less than 12 g sec, VSS less than 35 mph, and the PCM detected the IAT sensor indicated less than -38ºF for a period of 3-20 seconds. The IAT sensor is a variable resistor that includes an IAT signal circuit and a low reference circuit to measure the temperature of the air entering the engine. When the IAT sensor is cold, its resistance is high. When the air temperature increases, its resistance decreases. With high sensor resistance, the IAT sensor signal voltage is high. With lower sensor resistance, the IAT sensor signal voltage should be a lower voltage.
Cause and Solution
IAT sensor signal circuit is open between the sensor and PCMIAT sensor signal circuit is shorted to VREF or system powerIAT sensor is damaged or has failed (it may be open)PCM has failedTSB 02-06-03-005 contains a repair procedure for this code
Video Guide
Diagnostic Info
- DTC Code: C123
- Brand: GMC