FixVault

Possible Causes

Possible Causes 
(K21) IAT SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
(K21) IAT SIGNAL CIRCUIT OPEN
(K900) SENSOR GROUND CIRCUIT OPEN
IAT SENSOR
PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. See  DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure  .