I replaced the EGR valve on my 99 Monte Carlo, but the CarMD still displays a code PO401. How do I clear the code and reset the engine idiot lite code? Also is replacing the unit all that is needed for this repair, where will there be any more blockage to deal with or clean? Thx G
Diagnostic codes, for the most part, help to determine what system the vehicle is having a problem in. Having a code for the EGR system does not necessarily mean to just replace the EGR valve. EGR systems can be controlled by vacuum or electronically. Once you've properly diagnosed and repaired the problem, to clear the code and turn the engine light out, you should use a scan tool.
〉 Answered on Jun 16th, 2008 by Suzanne Grego, Technician at City of Philadelphia Fleet Management