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Great job by 9milly7 in posting how to clean the EGR ports. My 1995 Millenia 2.5L engine with 140K miles had the same problem. The right port was totally closed with carbon deposit. The left port just has a small <1/8" hole remaining. I took both the input throttle and EGR valve as described and clean them with a scapper and carburator cleaner. I'm pretty sure the blocked EGR ports were the main cause of the followings:
1. OBD code P0400 (EGR system flow)
2. OBD code P1195 (Baro/EGR boost sensor)
3. High Nitrous oxide emission, almost failing California smog inspection

I have all three of these problems. I would have saved $500 in replacing the EGR/Barometric sensor if I had known about cleaning the EGR ports. Replacing the old EGR/Barometric sensor with a newer, more sensitive sensor did remove the P0400 and P1195 codes and did make the check-engine light dissappear. However it did not help in reducing the nitrous oxide emission.

I want to add the following notes to help others to clean the EGR ports and the EGR valve more easily:

I) To remove the input throttle easily, do:
1. Remove the battery.
2. Remove the air cleaner top assembly and the fitting/hose/pipe from the air cleaner assembly to the input throttle.
3. Remove the electrical connectors and gas pedal cable around the input throttle to get access.
4. The hose connected to the bottom rear of the input throttle does not need to be removed before removing the throttle. This hose is hard to remove. Just pull the input throttle out to the front with enough force to take the throttle out of the top two mounting screws.

The EGR valve does not need to be cleaned. My 140K miles EGR valve looks reasonably dry and clean. However, you can remove the EGR valve to check that the air can flow from the EGR ports to the EGR valve easily. You can use compressed air blower to check air passage by blowing into the EGR port. The air will be blown back to the opened mounting holding the EGR valve.

II) To remove the EGR valve easily, do:
1. Remove the electrical wire and mounting bracket on top of the EGR valve to get access.
2. Remove the vacuum hose on top of the EGR valve.
3. Remove the EGR valve mounting bolts.
4. Remove the EGR hose feeding into the EGR valve. This hose is dotted red.
5. Remove the water hose feeding into the EGR valve. This hose is not dotted red.

Now I'm very confident that my car will have low emissions :D . I had replaced the 2 pre-catalytic O2 sensors at 122K miles and noticed a significant reduction in carbon monoxide (CO) and hydrocarbon emissions (HC) (also noticed better fuel efficiency). I think a fully functioning EGR system will definitely reduces the nitrous oxide significantly.
 
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