Diagnostic Aids
When attempting to diagnose an intermittent problem, use scan tool to review malfunction history diagnostic information. The data can be used to duplicate a problem.
With ignition on, engine off, the MAP sensor reading should be the same as barometric pressure (no vacuum-high voltage). Comparing this reading with a known good sensor is a good way of verify accuracy of suspect sensor. Readings should be within .4 volt. See MAP SENSOR VOLTAGE table.