My wifes car has the check engine light coming on.
The code says it's the EGR valve not having sufficient flow.
We had the valve replaced but they never cleaned out the pipe it connects
to which we were told needed to be done. So is there anything we can put in
with the gas to clean it? Like these additives you can buy. Or would we
have to take it to a garage to have it cleaned. We've been quoted 'about'
$600 to have this done which seems really high.
"I don't care who you want to speak to, or how far you came, or what you
I am going to assume that the Mystique EGR system is similar to that
used in my Focus. The topic 'Insufficient EGR flow' comes up on
various Focus forums a fair amount...
It's a reasonably good possibility that the EGR flow is sufficient,
and that the problem actually lies in the DPFE (Differential Pressure
Feedback EGR) sensor. This is a solid-state sensor that measures
the pressure drop across an orifice in the EGR tube. By measuring
the pressure drop, the computer can calculate the amount of flow.
These sensors are notorious for going bad. I would check out the EGR
pipe for obstructions, make sure the pressure sampling ports are clear,
and the rubber hoses connecting the ports to the DPFE sensor are also
clean and in good shape. If there's no trouble found there, you may
need to have the system diagnosed (there's also a solenoid/regulator
valve controlled by the computer that controls the vacuum supply to the
EGR valve) to see if either the DPFE sensor or vacuum regulator valve
are bad. If you want to shotgun the diagnosis by parts replacement
instead of paying for someone's time, I suppose you could replace
those parts. I'd replace the DPFE sensor first, if the tube(s)
all check out.
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