This is a common problem for Contours/Mystiques.
If you search the forums, you will find plenty of posts on CEL P0401.
Unfortunately, there is no simple solution to this problem, since there are many components that make up the EGR system.
Here are some of the reasons for a P0401:
- Vacuum hoses for EGR system are clogged, loose, or have leaks
- EGR (exhaust gas recirculation) valve clogged or stuck
- EVR (EGR vacuum regulator) solenoid is not functioning (i.e., opening) correctly
- DPFE (differential pressure feedback EGR) sensor not functioning correctly
- EGR passage in UIM (upper intake manifold) clogged (you would not drill out this part though)
- EGR pipe (from EGR valve to exhaust manifold) is clogged
1996 Contour SE Sedan 4D (Royal Blue)
Duratec V6 2.5L 24-valve DOHC
Automatic
75,000 miles
No Mods (unless you call the DMD a mod)
Replaced EGR valve (gunked up), EVR (EGR VR), PCV valve, and evaporative emissions hose (cracked).
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