Idle Air Control Valve trouble!


I have a 1997 Mazda Protege, automatic with 85K on it. as the cold weather set in it started giving starting trouble. It would not start unless I applied a bit of gas. This was an intermittent problems last winter, but I lived with it. Then today morning same thing happened and the check engine light came on. Drove in to the nearest mechanic and he tells me its the Idle Air Control Valve. Supposedly it needs replacement and would cost ~$650 with labor .

My question is (a) is this a correct diagnosis (b) does this sound like a reasonable expense for this part ?

Thanks a lot

It would be useful if you posted the actual error code (like P0123). If the mechanic does not want to tell you want it was, some auto parts stores will read them for free (they don’t get all the VW codes, but they get most of them. Try Autozone or Advanced Auto Parts.

I did not get the code. but I was told this shop prints the code and diagnosis when he writes up the charges. I will post it soon. What I wanted to know was does the starting problem sound consistent with what he diagnosed.

mazdagal, it does sound like the IAC valve is the problem. The only question is whether it should cost 600 bucks to replace it.

On my 87 Ranger & 97 Explorer the IAC is a 60 buck part at any auto parts store. On the Ranger & Explorer replacing the IAC is a VERY simple 5 minute job.

This would be the perfect time for you to go to an auto parts store & pick up a Haynes manual for your Mazda. About 20 bucks.

Now read the step by step instructions for replacing the IAC valve.

If it reads something like this:Remove electrical connector & two screws from IAC valve & remove the valve, then this is NOT a 600 buck job.

OTOH, the Haynes manual might show that replacing the IAC on a 97 Mazda is more involved then this.

I agree with 87_Ranger that replacement of the IAC is typically a simple job with an inexpensive part. I replaced the IAC on my Dodge as a DIY job. The part cost about $48 from AutoZone and installation was straightforward. The repair might not be as simple for your Mazda but you should certainly get a second opinion before giving your mechanic the go-ahead.

I called up a couple of Mazda dealers in the area, one said 570 inc. labor, and another 520 installed ! I try to avoid dealers because i think they always take you for ride. but this time it seems the other way round.

On my 2002 Toyota Sienna, that IAC is buried down inside the throttle body and there is a major tear down to get at it. While it didn’t cost quite that much, it was close. Better look at that car, not some other model, which is meaningless.

My old 1989 Dodge Caravan, that thing was right out in plain sight, and very little work. Not so on my Toyota, and I am guessing it is buried on his car as well.

Click on this web page at Auto Zone auto parts:,APP445140/vehicleId,2350001/initialAction,partProductDetail/store,505/partType,00207/shopping/partProductDetail.htm As you see, the price there is $313 . The price at a garage automatically increases 150% over this price. That makes it about $460. The part is a little (not, a lot) more work to replace than the idle air control valve on most other cars. One thing you could try is an iac valve spray cleaner. Pull a rubber vacuum hose loose that goes to the iac valve and spray the cleaner in. Let it sit a few minuets. Start the engine. Repeat. Auto Zone, and other auto parts stores, will read (scan) the check engine light for free. When they do, bring the codes here for advice.

UPDATE: the code that the mechanic read was P0505. he charged me a hours worth diagnosis and figured the IAC is malfunctional.

The dealer offer seems tempting to me (~ 70-100 bucks cheaper), but I am thinking, once the car sees the dealer shop , the bill wont stay at that.

The code it gave was P0505. The mechanic erased it though.

If you aren’t comfortable with the mechanic, or the Mazda dealer, go to the bottom of this page, click on Actual Car Info. On the new page, scroll down to Owning? to Mechanics File. Put in your zip code and the distance you’re willing to travel. Several mechanics/shops, with comments from customers, will appear. Choose. Call. Talk.