Note On Intermittents:

WARNING: This page is about a different car, the 1986 Oldsmobile Toronado and 1986 Buick Riviera. However, it is still accessible from the selected car via links, so may be relevant.

If an intermittent Code EO38 is being set, manipulate the related wiring while observing engine data parameter ED05. If the failure is induced, the "MAT" reading will drop from its normal valve to the "open" reading of -35 to -40°C. This will help to isolate the location of the malfunction.

Fig 1: Code E038, Manifold Air Temperature (MAT) Sensor Too Low

Fig 2: Code E038, Schematic