2004 Mazda MPV Stalling and Rough Idle: Replacing the Idle Air Control (IAC) Valve

I have owned a 2004 Mazda MPV LX since early 2006, and it has been a great vehicle so far. Plenty of room, fairly fuel-efficient, quite practical and very satisfactory on the whole… with one exception.

Starting around late 2007, the minivan started to occasionally stall while decelerating or braking. The RPMs would drop to near-zero and the engine would die. It only happened a couple of times over a few months but began to get more and more frequent as time passed. Generally it would only happen between 15 and 50 MPH, and only when letting off of the accelerator. After the first few times, I learned to avoid it by tapping the gas as I saw the RPMs plummet; if I did that in time, I was able to keep it from dying. If I didn’t however, my only recourse was to shift into Neutral, start the engine while rolling, shift back into Drive and keep going. Of course, this was quite unsafe, and by the time it was stalling once or twice every time I drove it, it was time to do something about it.

I did a bit of research online and found the occasional mention of a faulty IAC valve being the cause of stalling and rough idling. The folks at Kragen didn’t know what an IAC valve was, and I didn’t pursue it any further from there.

The van began to show a check engine light, so I took it in to the local Mazda dealership to have them check it out. It turns out the check engine light was the result of a sensor that was blocked by excessive carbon buildup in the intake manifold, which was caused in part by the stalling behavior. According to the tech, the stalling was causing the engine to run a richer fuel/air mix on restart (because it interpreted the stall as an indication of a fuel/air mixture that was too lean), and this frequently-richer burn was causing an undue amount of carbon buildup. They cleaned out the intake manifold with Seafoam (or a product like it), did a firmware upgrade, changed the plugs and wires (which I’d asked them to do as a maintenance step while they had it in there), and, $1,100 later, was given a clean bill of health. The MPV passed Oregon’s emissions testing, the stalling was gone and all seemed well.

A couple of months later, the stalling started to act up again, and grew in frequency as it did before. I did a bit more research and all available evidence still pointed at a faulty IAC valve. As it turns out, the folks at Kragen weren’t able to find the part I was referring to because it seems to go by several name/acronym combinations: IAC valve, idle air control valve, idle control valve.

Still not sure that a fix was in sight but willing to try it, I ordered a replacement IAC valve from an online parts retailer for around $65 and put it in. Replacement of the valve was very easy; it is attached to the intake manifold by two bolts, and has a simple wire harness attached to it. Here are two pictures showing its location on the engine. I saved these when I was doing my research and, unfortunately, can’t find the original source, but here they are:

Location of idle air control valve on MPV engine

Location of idle air control valve on MPV engine

Closeup of IAC valve

Closeup of IAC valve

As you can see, the valve is fairly easy to locate. It should be in a similar location for the following years:

  • 2002 Mazda MPV
  • 2003 Mazda MPV
  • 2005 Mazda MPV
  • 2006 Mazda MPV

Years 2001 and earlier have the IAC valve attached to the firewall, but it should not be too difficult to find (the part itself looks the same as the one seen here).

Since installing the replacement valve around four months ago, the minivan has been running as good as it did when I bought it. There have been no issues whatsoever with stalling or rough running.

Pick up a replacement IAC valve from Amazon using the link below. The part is listed as being compatible with a series of Ford cars; however, the engines are the same and this will work for any 2001+ MPV.

Update: Slightly better image of the IAC valve below.

It's the gizmo with the red circle around it.

It's the gizmo with the red circle around it.

106 thoughts on “2004 Mazda MPV Stalling and Rough Idle: Replacing the Idle Air Control (IAC) Valve

  1. I changed the IAC on a Mazda MPV and it repaired the same problem. Thanks for your advice. You saved me time and money.

  2. I have a 2004 MPV that started suddenly having a rough idle problem (engine vibrate more than usual) with no check engine codes.At the same time I can hear a small clinking sound in the back exhaust around the TWC (Three Way Catalyst). The down pipe that is after the Catalytic converter and before the TWC become red hot and I am not sure what is causing that. I have recently changed all the spark plugs and checked all the coil and they were within specs. I have also changed the vacuum hose that was the reason for a recall on previous models and changed the AIV that has been mentioned here. I am not really sure what is causing this problem and I am not driving the van because the risk of fire from the the exhaust. If anyone have this problem or have any ideas, would you please share your thoughts?
    Thanks for such a helpful post.

  3. I ve same problem. I’ve I replace the coil and the IAC valve it still is shutting down on me especially at the stop sign it retains the RPM if I leave it in neutral as soon as I put it in gear it drops and styles I am ending up having to do I use my left le5g for the accelerator for the brake. Any thoughts please

  4. Big thanks for this blog. Even after spending few hundred dollars on various things on my mazda 2004 mpv, the stalling problem was reappearing many times in the past. I was about to buy new car then came across this blog. Wish I read this article couple of months back..Not only IAC valve replacement fixed the stalling issue but also driving seems like much smoother than before. Thanks again..

  5. I replaced my IAC in the mvp 2004 Mazda because it was idling oncr I replced it its still doing the same thing could you tell me what else it could be?

  6. I got a 2000 mazda mpv dx. At first it could not get it to go over 25 mph and could not make it up a hill without stalling out . first garage replaced the plugs and air filter didn’t make a difference. decided to try another garage, I was told the fuel pump dropped its pressue when excelerating. He tried a new fuel pump still no difference. also checked the catylac converter. The codes that are showing are H2 os bank 2 senser, which was replaced no diiference. The other one showing is p0102 massor volume air flow. Mechanics said this would not cause the problem? put fuel injector cleaner in and put extra fuel in it still nothing.
    as a last result we got a back yard mechanic look at it he took out a plug that had something to do with a mass senser plug and it worked for about 20 minutes able to get it to about 80 mph then it started to stall again. Any body with any ideas? shes at another garage now and they think the crack in the maniold may be causing it

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