It's much more likely to be a defective DPFE (the flow sensor) than a
clogged EGR. The DPFE can be tested with a vacuum pump and voltmeter, or, if
you like taking risks, just replaced. But first make sure that everything is
properly connected and the tubes leading to the DPFE are not clogged.
Like others have said, the most common cause is a defective DPFE sensor. You
a "down and dirty" test of the EGR. Pull the cap and foam filter off of the EVR
vacuum solenoid), put your finger over the nipple with the car idling. This
vacuum to the valve and the engine should stumble or stall. This tells you the
is at least working.
I'll have to agree with Happy Traveller.... the DPFE is, by far, the most
common cuase of this particular code (I'm guessing P0401....). Please,
folks, try to realize that OBD2 is NOT cut and dried. All codes require some
form of diagnostics to ensure that we aren't going to replace parts
In your case, the PCM is seeing "low or insufficient EGR flow". You are
expecting the PCM to be telling the truth. While the PCM thinks it's telling
the truth, it is more likely that the DPFE sensor is lying to the PCM and
the PCM will, in it's own turn, lie to you.
What he said. Hence the phrase GIGO - "garbage in, garbage out".
I've replaced the DPFE twice already on our 2000 Taurus wagon. The 2nd
one went the same day it passed inspection in 2004, after it passed and
on the way home. Wondering if the state equipment had anything to do
with it failing.
Could be the sensor. Start engine and take hose off going to egr valve
apply vacuum to valve (opens valve) and engine should run rough or stall.
If it does then the sensor is bad. If there is no difference, then the
valve or the passage way is plugged. Take the egr valve off and you can see
if it works with vacuum. Plug the hole in the intake manifold and start
engine, there should be LOTS of vacuum at the hole and you should get some
exhaust at the tube the goes into the bottom of the valve. If not, the
passage is plugged. I use a drill and a length of speedometer cable to run
through the intake manifold.
All this is not hard to do if you want to save a few bucks. The sensor is
It was last winter when I got it. Probably simple economics at work,
given the recall, number of vehicles affected, number that failed,
etc., the huge boost in production numbers for this component probably
drove the price down significantly. Who knows.
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