Fail-safe Function
WARNING: This page is about a different car, the 2006 Acura MDX, 2005 Acura MDX, 2004 Acura MDX, and 2003 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.
When an abnormality occurs in the signal from a sensor or from another control unit, the PCM ignores that signal and assumes a pre-programmed value that allows the engine to continue running. This causes a DTC to be stored and the MIL to come on.