Note. For circuit reference, see DTC P0101 schematic.
Circuit Description
EGR operation will cause variations in MAP sensor because when EGR valve opens, exhaust gas is drawn through it with intake manifold vacuum. When all test enable conditions are met, the test begins with PCM cycling the EGR from off to on and on to off, and recording the change in MAP. The PCM then converts MAP change to percentage and calculates the MAP error, or the difference between the actual percentage MAP change and the percentage MAP change that the PCM expected to see. The PCM performs this test several times to gain an average. If at least 8 tests have occurred, PCM compares its current average MAP error to the failure limit.
For EGR "off" test, if the current average MAP error is 6 kPa or greater, DTC is set. If error is less than the limit, EGR operation is returned to normal software control.
For the EGR "on" test, if at least 8 tests have occurred, the PCM compares its current average MAP error to the failure limit. If current average MAP error is 7 kPa or greater, DTC is set. If error is less than the limit, EGR operation is returned to normal software control.