P401 code/EGR something

ford
taurus

#1

On my 1998 Ford Taurus with 132000 miles and a bad head gasket I got my service engine light going to work. I stopped at a Autozone and they read the code and it was a P401. The slip of paper says EGR system fault, the ECM has detected to little flow on EGR system. So my question is:



What does this mean? It listes probable causes as Blocked passage on EGR system, or failed EGR valve or EGR solenoid faulty or failed EGR pressure sensor where applicable or Failed EGR position sensor where applicable.




#2

“probable causes as Blocked passage on EGR system, or failed EGR valve or EGR solenoid faulty or failed EGR pressure sensor where applicable or Failed EGR position sensor where applicable.”

This is pretty much what it means. All of these things need to be checked and tested. My own guess/assumption would be the pressure sensor (DPFE sensor) just b/c Ford have had tons of trouble with these.

But that is just a WAG. You can spend a lot of money trying to replace parts. If you have a repair manual it will give you the diagnostic steps to sort it out.

EGR - btw - is “exhaust gas recirculation.” At certain times portions of the exhaust are sent back through the intake to be burned again. It reduced emissions. You computer is reading too little exhaust flow in the system.


#3

How do they figure out what it is? Just wondering what happens if you don’t fix it?


#4

Who are “they”? You mean a shop? “They” follow a set of steps to test each piece. E.g. the mechanical operation of the valve itself is simple to test with a vacuum pump. It has electricals that need to be tested. The DPFE sensor has to get and send information - that can be tested. So I’m not sure what you’re asking.

If you don’t fix it it is likely that nothing will happen - esp as compared to a bad head gasket. Except that you will pollute more. Some people don’t care. I do.


#5

Given all the other problems that you have with this car, I would just leave the EGR problem as-is. (It’s probably the DPFE sensor.)


#6

Actually the old beater has been running real well. In fact it made it through the winter with no issues. I am also noticing I am not losing as much antifreeze as before and the engine sounds smooth. I am still getting good gas milage. I got this code now and just wasn’t sure what this EGR unit/problem did. I don’t live in a state that requires emmission checks and didn’t know if the car would stop running with this issue.


#7

I wasn’t sure how something like this was tested and such, does it take special equipment or can basically any mechanic do it? I like to keep my car running at it’s best even with a bad head…


#8

It is very unlikely to cause any operational problems. If it starts to ping slightly under light load, then that might be a symptom of an EGR defect.


#9

That’s why I said you need a repair manual. It will tell you. Mostly you will need a multimeter, though a hand vacuum tester/pump will also come in handy.