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ttiger79, Auto mechanic
Category: Ford
Satisfied Customers: 1257
Experience:  ASE Master Certified, Advanced Level Engine Performance
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I have 1997 ford escort.check engine light on,code ...

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I have 1997 ford escort.check engine light on,code p0401.exhaust gas recirculation,insufficient flow.what could this problem,and what do i need to do to fix this problem?
There's quite a few things that can cause this code to be stored in your computer. I can point you in the right direction to diagnose this yourself.
First thing to check is the vacuum line going to the EGR valve. There is a TSB outlining a concern where the vacuum line is routed poorly, causing it to be pulled from the valve. Here's a diagram:

This is a common problem.

If this is good, the other real common problem is the DPFE sensor. This is the sensor that detects the difference in EGR tube pressure when the valve is opened. If you have a volt meter, I can tell you how to test this sensor.
Customer: replied 9 years ago.
i have replaced egr,map,and other sensors. vacuum hose to egr in right direction.where is the dpfe located?
The DPFE is located by the EGR tube. You can see it in the diagram that I posted for you earlier. It's at the top of the diagram with the arrow pointing up. It has an electrical connector going to it, and two rubber tubes that run from the EGR tube to the sensor. When you locate it, tell me which one you have in your car (square metal or black plastic) and I can tell you how to test it.
ttiger79 and 4 other Ford Specialists are ready to help you
I see you accepted my answer. Thanks!

If you would like to test the sensor before replacing it, just let me know which one is installed in your car, and I can give you a test procedure! I can understand your frustration with this code!
Customer: replied 9 years ago.
i have the metal one
Backprobe the light green wire with the white tracer that is attached to the connector on the sensor and test the voltage of this wire with the key in the on position- engine off. Tell me what you see.