Question about Cars & Trucks
P420 is EGR system malfunction P1406 is EGR pintle position problem be sure and check power and ground before condemning the valve and the P401 is catalyst code i would fix EGR code first clear monitors and run a drive cycle to see if the cat code returned although the egr and catalyst are separate systems an EGR that isn't functioning may cause the emissions levels to be too high for a marginal converter to diffuse resulting in the cat efficiency code
Posted on Dec 10, 2012
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Posted on Jan 02, 2017
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