2000 Mercury Sable engine light won't stay off

Tiny
DEBBIESABLE
  • MEMBER
  • 2000 MERCURY SABLE
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 87,000 MILES
When checked a PO401 code came up. Purchased & had the part installed & reset computer. after a few miles the check engin lite came back on. Checked code again & it was the same code. Reset & drove again & lite came on again. My car canno pass the emmissions testing center for new tags because the code will not go away. I am stumped & s is the mechanic.
Help, please. My car seemsto run goodd, just sing a little more gas than usual.
Debbie
debbie.Heughan@comcastnet


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Sunday, July 25th, 2010 AT 7:38 PM

3 Replies

Tiny
RASMATAZ
  • MEMBER
P0401 OBD-II Trouble Code
Technical Description
Insufficient EGR Flow

What does that mean?
EGR stands for Exhaust Gas Recirculation. It is part of the vehicle emmissions system, and is used to reduce combustion temperature and pressure to control Oxides of Nitrogen. There are generally three parts to the EGR system: the EGR valve, an actuator solenoid, and a differential pressure sensor EGR (DPFE). These things work together to deliver the correct amount of recirculation based on engine temperature, load, etc. The P0401 code means that OBD detected an insufficient amount of EGR.

Symptoms
You may notice drivability problems such as pinging (a.K.A. Pre-ignition knock) when the engine is under load or the vehicle is at higher speeds. There may also be other symptoms.

Causes
A code P0401 most likely means one or more of the following has happened:

The DPFE (differential pressure feedback EGR) sensor is faulty and needs to be replaced
There is a blockage in the EGR (tube), most likely carbon buildup
The EGR valve is faulty
The EGR valve may not be opening due to a lack of vaccuum
Possible Solutions
In fixing this code, it is quite common for people to just replace the EGR valve only to have the OBD code return. The EGR valve is not always the culprit.

Use a vacuum pump and pull the EGR valve open while monitoring engine RPM's & DPFE voltage. There should be a noticable difference in RPM's with the EGR open
Clean out the EGR valve and/or tubing to remove deposits
Check the voltage at the DPFE, compare to specified values (refer to a repair manual for your specific model)
Replace the DPFE sensor (with a good quality / OEM one)
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Sunday, July 25th, 2010 AT 11:22 PM
Tiny
DEBBIESABLE
  • MEMBER
Thank you for your quick reply, I will ass ths info on & see if they can get it resolved, what you are saying makes sense. I will let you know if it works.
Blessngs
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Monday, July 26th, 2010 AT 12:02 AM
Tiny
DLMAY277
  • MEMBER
My car is doing the exact same thing, 2000 Sable LS. Replaced the EGR and code still reads the same. I was finally able to reset the code, drive for 70 miles, get it tested and it passed emissions. When I drove away, literally 1 mile down the road the light came back on. It won't go off. I've had everything checked.
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Saturday, August 7th, 2010 AT 7:01 PM

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