Check engine light is on. After having a computer put on it. It comes back with a P0400 error code. Im really trying to save some money on this with out being over charged on it, The car is not getting good gas mileage at all. What can i do my self, Im not a mechanic here but willing to learn how i can do this my self. Thanks for the help.

 

Here is a page on what the code P0400 means...The EGR valve.

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There have been some problems with the EGR valve on some early production Protege that can be checked with an ohmmeter if you are able to. Is easier to remove the valve in order to check. This EGR valve does not use a vacuum diaphram to open the valve but instead uses four separate magnetic coils to control position. It is the resistanace of these coils you can check. Have also run accross a few with a bad connection at a connector between the valve and PCM. Will see if I can locate a early Protege so I can take a pic and show you the location of the connector.

 

Thanks for the reply babyhuey... ill wait for you to reply again.

 

Here are some picts of the connectors. The first is a not so good picture of where the EGR valve is located. If you look back there you will see the valve with a 6 pin connector on it. The second two are the location of the connector that I have seen a few problems with. The four wires in this connector are the wires that the computer uses to control the valve position. Check and make sure there is no corrosion or moisture in here and pins are making good contact. The last is a picture of the boost sensor which is the actual sensor that the computer uses to determine if the EGR valve is opening as expected. The solenoid just to the right of this is used to switch vacuum source to boost sensor between checking the EGR and looking at manifold pressure and atmospheric pressure.

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Did not have enough room to upload the diagrams to check the resistance of the coils inside the EGR valve so will make another post. The first diagram is the electrical schematic of where the wires go inside the valve so you will getthe idea of what you are checking. The second is the connector on the valve as it would look with the electrical connector disconnected. Use a DVOM to check the resistance between the each of the pins as follows. Between pin C and pin E, between C and A, D and B, and D and F. The resistance readings should all be very close to the same reading of 22 ohms. The Mazda NGS or WDS testers could be used to actually manually open the valve in steps to see if it was working properly but since you do not have access to one then will have to just disconnect the negative battery cable after inspecting and cleaning the connectors in previous post and drive to see if code comes back. An EGR valve not operating should not effect your vehicles mileage however so there may be other problems there. Post back if I lost ya along the way anywhere.

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