READ SOMETHING THAT SAID IT MAY BE CAUSED BY POWERTRAIN CONTROL MODULE HOW WOULD YOU CHECK THIS AND REPLACE SUCH ITEM
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2003 Chevrolet Impala Question: CHECK ENGING LIGHT ON REPLACED EGR LIGHT CAME BACK ON
What are the Diagnostic Trouble Codes? Computer failures are not that common, it does happen, but not a primary cause.
Replycleebill, December 16, 2013, 12:38Rookie
Replytires too, December 16, 2013, 15:44Journeyman
A P0401 is an Insufficient EGR flow code. have you checked the EGR ports for carbon build up? You probably are not getting vaccum to the EGR valve.