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Discussion Starter #1
I'm checking out an EGR code P0401 on a Toyota Camry 1996 2.2L 4 cyl.
Found great info on line re how to test, how it operates but from what I read and see it appears on this vehicle the only wired connection to this system is the VSV valve that switches Vac on to EGR from modulator.
Saw some have a temp sensor in exhaust gas feed sending rise in temp when EGR vales is open. But don't see that on this model.
Curious
How does this system get monitored? What is the feed back to the control mod ECM so I knows is there is or is no recirculating and weather it sets the code?
Thanks
Scott
Missing the good old days w my cars.
 

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ASE CMAT L1 MRRT
09 Avalon XL
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820 Posts
how it works

From what I have learned, the PCM monitors EGR operation by opening the EGR valve on deceleration. It looks for a change in the MAP sensor output.

The EGR vacuum modulator senses engine load by measuring backpressure in the exhaust system. The modulator then sends a regulated vacuum signal to the EGR valve which opens the valve a specific amount controlling the amount of exhaust gases that are allowed into the intake manifold.
 
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Discussion Starter #3
Thank you. I needto read up on the MAP then

Thank you
I need to read up on the MAP. So if the MAP is bad logically sounds like that could cause the p0401 code if the system is not reading the change in that.
thank you I appreciate your reply
 
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