P0401 and P0402 I think have to do with the EGR Valve and EGR Sensor-However even though its one of the EGR problems" P0401" it is better to buy the sensor and the EGR Valve b/c you don't want another EGR problem again.-But I strongly suggest that its the EGR valve.-Sensors are usually the next break down-"a employee's friend at autozone has a mustang". Or someone came back b/c of another problem occured later.-Autozone knows the codes so as them.
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Tuesday, January 20th, 2009 AT 11:54 AM