view topic – egr removal on 2000-2001 mazda mpv wd gaster x reader


It’s not necessary to remove the EGR to clean it. On my 2000, you can remove the top of the EGR using a stubby screwdriver. The part you need to clean comes off with the cover. Simply unplug the harness, remove the four screws and lift-off. This way, you’re not having to wrestle with the pipe connection and risking snapping it off. The EGR is a simple electro-magnetic device and isn’t a wear item.

If your car has 100K miles, it’s more likely that the EGR port in the intake manifold is plugged solid with carbon. Replacing the EGR valve ($200+) will not cure a vacuum problem. The port is a semi-circle that is machined into the manifold around the throttle plate. While it’s also possible to clean it by only removing the throttle body, I found it easier to remove the manifold and then separate the TB. Clean it with carb cleaner, a stiff wire and brush and EGR vacuum will return to normal.

What you want to clean in the inside of the valve where all the carbon from the exhaust builds up. The motor actuator you removed controls the plunger inside the EGR which can get stuck. Also if the EGR boost hose gets plugged you will a check engine light with an emissions related code.

I agree that removing the actuator provides more limited access but by operating the plunger and spraying /soaking it with cleaner I think you can get the chemical inside. Also you can clean the EGR internals by spraying cleaner through the orifice that’s connected by a small hose to the boost solenoid. But, I found that even after cleaning it this way I still had weak vacuum at the boost orifice. That’s when I discovered the plugged port inside the TB. With high miles (my ’00 has 196K) the semi-circular channel in the manifold was clogged solid. After cleaning it, my OEM EGR system now works as it should and it consistently passes my state’s emissions inspection (as recently as last month).

I follow your instructions to clean EGR on my 2001. I unplug and remove the actuator. I also disconnect the small hose from a plastic coupler (the hose sticks to the extension. I poke the small tube of carb cleaner into the plunger spring, and spray while repeatedly pressing the plunger. I also poke into the small hose toward EGR, and pray several times.

The easiest way to clean it is to pull off the rubber hose and spray carb or fuel injection cleaner while the engine is running. You’ll know it’s clean if the engine stumbles while spraying. If it doesn’t stumble, the orifice, EGR or internal port that runs around the throttle body is clogged. If you have high miles then I suggest pulling off the throttle body assembly and cleaning the port when it’s off the car. It’s probably full off hardened carbon. A mechanic may tell you to replace the EGR – it’s expensive – but if the internal port that feeds the throttle body is full of carbon a new EGR valve won’t do anything. Good luck.

4. After taking the top part (step motor) of the EGR valve, I realized what the real problem was. It’s the plunger that is stuck closed. The plunger does not move freely. It’s probably due to carbon on the plunger shaft that’s inside the valve body.

Yup, I did like maz2000. I’ll add some more details here. In my case, P0401 started appearing last fall, only after I was running at highway speed and that the engine was at temperature. If I did just small city rides, the CEL would even turn off. I cleaned the whole throttle assembly and intake manifold two years ago, so it could not be just a clogged EGR passage in the manifold, as some show on youtube. At the time I tried removing the EGR valve for inspection but was afraid ($$$) to break the pipe to the exhaust. So now there was something around the EGR.

According to Mazda, P0401 appears when the turbo boost sensor (which is only used here as an absolute air pressure sensor) when it does not measure a difference in intake manifold pressure after the EGR valve operates. The EGR function is only used when the engine is at temperature. A little tube brings the air pressure from the "out" of the EGR to the turbo boost sensor, through a valve that also allows to read the atmospheric pressure. When EGR is closed, the sensor acts as a MAP to monitor and contribute to the control loop equation to the fuel injectors. When the EGR opens, the manifold vacuum reduces a bit and the Boost sensor shall be able to read a difference. This is how the ECU concludes that something is wrong around the EGR. So check the tubes, the 2-way valve and the boost sensor. In my case they were okay, so back to the EGR valve itself.

Removed the connector, then used a vise grip to popstart the four little screws that secure the stepper motor, as I was afraid to destroy those philips #2 heads. The valve stem was completely stuck. It would normally move with just a small finger press and the spring under would bring it back up. Because of restrained space, I improvised a little hammer with a visegrip and a screwdriver bit, to hit the stem (not the metal cup) and then use an angled screwdriver to pull the stem back up. Keeping it moist with wd40, it took over 30 mins of push-pulls before it was moving freely upon a finger push. I reinstalled the stepper, connected it, and no more CELs and P0401. The stepper motor was still good. So great thanks to maz2000, it made my day.