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Word of caution - EGR valves and Exhaust
Systems get very hot. Disclaimer
What is an EGR valve for heavens sake? EGR stands for "Exhaust Gas
Recirculation. Some of your exhaust is fed back to the engine through a valve
(usually vacuum operated) to lower combuston temperatures and reduce NOX pollutants.
As your engine wears, horrible black grunge builds up in the EGR and closes it
off like an artery. The net result is .. you fail the emissions tests -
Wonderful.
Mechanics love them. Why? Because they can clean them out, shine them up and
charge the living heck out of you for "emissions repair" Quite a
little cottage industry are EGR Repairs.
What is it?
"Definition: The EGR valve is the main emissions control component in the exhaust gas recirculation system. The valve is located on the intake manifold and meters a small amount of exhaust gases back into the intake to lower combustion temperatures....." Does not get any more boring than that.
So, as the main part of the vehicle emissions system, the EGR reduces combustion temperature to control oxides of Nitrogen ( NOx) being released.
When it fails it ... Causes Pinging or engine knock when the engine is under load.
A code P0401 means ....
There is a blockage in the tube going to the EGR, or from the EGR to the
intake (carbon buildup) from worn engine.
Maybe the EGR valve is bad - won't open perhaps due to a lack of vacuum
The EGR valve is easy to find. Follow the exhaust from the exhaust manifolds
and you will find a tap off them near the engine. Follow this to a valve that
seems connected to the intake - The EGR valve.
Replacing the EGR may NOT stop the code from returning. You should test the EGR
valve first.
Use a vacuum pump and pull the EGR valve open while monitoring engine RPM's.
Yes, you can suck it open with your mouth! Horrible, but doable!
A working EGR will cause a drop in RPM's or even kill the engine when you force the EGR open at
idle.(it's only supposed to open later on in the rev range)
Clean out the EGR valve and the tubes leading to, and from the valve (if any) to
remove deposits I like to hit them gently (ok hard) with a hammer - not
very efficient but fun as heck. All the black stuff comes pouring out. B12 will
sometimes clean it too, but not as much fun.
Replace the DPF sensor
Replace the EGR valve - if tests show it no longer works.
Feedback from Readers.
...... I am having one heck of a time finding a DPF sensor! All the "big" auto supply houses on the internet don't seem to have it (like Advanced Auto parts, NAPS, Pep boys) I wouldn't be lucky enough to think perhaps it came with the EGR valve........Lesil - Panama City, Fl
Reply from us....
Disclaimer
If you decide to work on a car, it might kill you. If you get under a car, it could fall on you, killing you. If you touch a really hot bit accidentally, it will hurt quite badly. You could die from your injuries. If you work on some else's car and you make it worse they could kill you. Drinking anything that comes out of a car is not advisable and could be fatal. Working on brakes might be a really bad idea. Others could die, along with you. Be careful. Most especially don't blame us. We told you. No, really we did.
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