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Drew
Drew, Super Mazda Tech.
Category: Mazda
Satisfied Customers: 2518
Experience:  19 yrs. experience. Mazda Senior Certified Tech, with Ford, Linc. & Merc. experience. ASE L1 Advanced Certified Master Tech.
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Mazda MPV: My 2005 Mazda MPV (90K) makes jerking motion while

Resolved Question:

My 2005 Mazda MPV (90K) makes jerking motion while driving and at stops when still in drive. Doesn't jerk when parked. Engine light came on yesterday. Went to Autozone. Code is P0403 - EGR valve stepper motor circuit malfunction. 1 of 3 probable causes: 1. open or short circuit condition. 2. poor electrical connection 3. faulty EGR valve.

Valve is approx. $180

What can be checked before buying new valve? I'm fairly handy but if it's a job best left to local mechanic please advice.
Submitted: 1 year ago.
Category: Mazda
Expert:  Chris (aka- Moose) replied 1 year ago.

Hello, I'm Chris. Thanks for visiting Just Answer.

 

I am sorry you have had to wait so long for the first contact. Sometimes this happens when the question you ask is not detailed enough or its just hard to address online. Many have viewed your post, but have passed. I am checking to see if you still need help.



I am not going to lie, this concern is not my strongest point, but I will do my best to help you. I have access to many repair sites, so at the least I can provide something to address at least part of your concern if it is not something I can address from memory and experience.



I mainly work in the last half of the day, so that is when I do all of my responding. If there is anything else you can add to your concern to help me out more so I can help you out in turn please do so in your next reply.



Once you get an answer, you will be prompted to rate me. You are rating my help, not the website, or answer. If you feel the need to rate negative, please save the rating so I can try again or find someone whom may be able to help better.



Thanks for using our site, we will do all we can to earn your business, again sorry we did not get to you sooner.



Chris

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Customer: replied 1 year ago.

I do still need help. It said 11 Mazda techs were waiting to help. Six hours later no help. If Mazda is not your line of expertise I'll pass thanks anyway. I think my original post is sufficient to describe my problem.


 


How do I get a refund if no Mazda tech wants to help me?

Expert:  Chris (aka- Moose) replied 1 year ago.

Often this issue is a broken wire to the EGR valve and not the valve itself.

 

Verify battery voltage to the EGR valve on the two White/Red wires. Load test the White/Red wires with a test light or a headlight and verify the volts drop minimal like 0.08 max. Unplug the PCM, jump power to one of the White/Red wires at the EGR valve with it plugged in and then ground each of the EGR valve control wires through an ammeter one at a time and measure the current flow of each winding. voltage divided by resistance will give you amps. Each winding of the EGR valve should have 22 ohms. The EGR valve ground wires are the Black/Orange wire at terminal 72 of the PCM, the Pink wire at terminal 73 of the PCM, the Red/Green wire at terminal 98 of the PCM, the Pink/Black wire at terminal 99 of the PCM. Probe one lead of the ammeter into one of the EGR valve ground terminals at the PCM and then ground the other lead of the ammeter to a good ground and read the ammeter for current flow. If you get different ohm readings there is an engine wiring harness issue between the EGR valve and the PCM.

Customer: replied 1 year ago.

I'll be frank your answer was cut and pasted from a service manual and is no way helpful to a non-mechanic. I need a Mazda tech that has seen this particular code and problem and can talk to a regular guy. Thank you anyway.

Customer: replied 1 year ago.
Relist: Other.
I need a Mazda tech that has seen this particular code and problem and can talk to a regular guy.
Expert:  Chris (aka- Moose) replied 1 year ago.

I gather you do not want to do any of the electrical diagnostics needed. If that's the case then inspect the wiring to the EGR for any chaffing or breaks. If none are found then replace the valve. Then disconnect the negative battery cable to erase the code. If it returns then the wire testing has to be performed because the fault is due to the wiring.

 

Customer: replied 1 year ago.

What about replacing the wiring altogether? It's got to be cheaper and easier than valve replacement. A friend suggested spraying connector with cleaner from RadioShack in case of corrosion and poor connection.


 


Can you let me know the wiring/connector part name and/or number so I can see if there available at NAPA or Autozone. Otherwise I'll order from dealer.

Customer: replied 1 year ago.

Why is this question closed? Why hasn't my question been assigned or opened to other Mazda techs? Please answer or I'll have to rate poor service.

Expert:  Chris (aka- Moose) replied 1 year ago.
Since you want your post opened to others, I will just opt out and let them try to help.
Customer: replied 1 year ago.

Sorry Moose I just didn't expect to wait 48 hours betwn questions. I need a more responsive tech and one familiar with this Mazda code.

 

I disconnected and reconnected electrical it made a noticeable click on reconnect. No noticeable chaffing or splitting.

 

I disconnected vacuum tubing to EGR valve. With engine running there is a strong suction. I assume this means the valve is not clogged.

Expert:  Drew replied 1 year ago.
Welcome to Just Answer. My name is XXXXX XXXXX I will be glad to assist you.

Sorry for taking so long to get a Mazda expert.

Every time I have had the P0403 fault code for this vehicle is has been caused by either carbon stuck holding the valve open slightly it a faulty EGR valve.

I suggest removing the EGR valve and check for carbon stuck holding the valve open. If it looks ok, you will need to just replace the EGR valve. It is easy to replace. Just remove the two. Opts and be careful not to drop the metal gasket.

Thanks
Drew
Customer: replied 1 year ago.

I've read quite bit on this over the last couple days. A few people changed out the EGR valve only to still have the same code. In their cases it was either the computer or wiring.


 


Can I spray carbon cleaner into the open vacuum tubing to loosen and flush out the valve?


 


Are the code reasons prioritized? I noticed faulty valve is third behind circuit malfunctions.


 

Expert:  Drew replied 1 year ago.
Spraying anything in there may help but a piece of carbon may very hard and take a long time to dissolve.

There is no prioritized in possible causes.

It is possible that you may have a faulty computer or wiring but that will require extensive electrical diagnosis and special scan tool to diagnose. The EGR is the cheapest and easiest place to start.

Thanks
Drew
Customer: replied 1 year ago.

It's still under warranty. The EGR valve isn't covered. I haven't called to see if the computer is covered. If it's covered I'll make sure the EGR isn't at fault before bringing it in.

Expert:  Drew replied 1 year ago.
Sounds good. Let me know if that resolves your concern or if you need any additional help.

Thanks
Drew
Customer: replied 1 year ago.

Am I running any great risk still driving it? Definitely don't want it to break down on wife and kids running errands around town.

Expert:  Drew replied 1 year ago.
No problem driving other than it may stall at stops or idle rough. Otherwise it will no cause any damage. You can also look into getting a used EGR valve from a salvage yard if you want to try and save some money.

Thanks
Drew
Customer: replied 1 year ago.

That's a great idea. Do you know what years are compatible with my 2005?

Expert:  Drew replied 1 year ago.
I do not know off hand but I can check at work tomorrow. If you call a salvage yard, they will know what years use the same EGR valve.

Thanks
Drew
Drew, Super Mazda Tech.
Category: Mazda
Satisfied Customers: 2518
Experience: 19 yrs. experience. Mazda Senior Certified Tech, with Ford, Linc. & Merc. experience. ASE L1 Advanced Certified Master Tech.
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