Code P038, Open Intake Air Temperature (IAT) Sensor: Action

PCM turns on MIL. PCM substitutes 104°F (40°C) for IAT when engine coolant temperature is 104°F (40°C) or greater or PCM substitutes engine coolant temperature of IAT when engine coolant temperature is less than 104°F (40°C).

1. If IAT sensor is open, PCM parameter PD05 should indicate -37°C or less. If PD05 does not indicate -35°C or less, sensor signal is not open. See NOTE ON INTERMITTENTS.
2. Checks PCM and circuit No. 472 from PCM to sensor connector. If PCM parameter PD05 indicates 148-151°C with connector terminal "A" shorted to terminal "B", sensor circuits and PCM are okay.
3. Checks for open sensor circuit No. 452 (ground).
4. Checks PCM's ability to recognize short to ground on IAT input.
5. Fault is most likely at PCM connector or PCM. Before replacing PCM ensure pins and connectors are not damaged.
6. IAT sensor can be damaged by backfire in intake or by excessive intake heat due to valve train faults. If vehicle has had multiple IAT sensor replacements, check for signs of backfire or high intake manifold air temperature due to improper valve train operation.