Hello folks, first post, new to forum but not to Nissan. I have an 01 Maxima 20th Anniv edition.

I recently acquired an 01 QX4 with 105k miles, should I replace the IACV with no signs of issues yet? I bought the part from rockauto and plan to do it myself as the quote from dealer was ridiculous as expected. When I called the dealer he made an interesting comment that they dont do a lot of these repairs, so should not jump in with the change just yet?

The OE Hitachi IACV is very reliable but the coolant gasket on the aluminum body is known to eventually leak, taking out the stepper motor when the motor get wet with coolant and too often wrecking the ECM in the process. Due to a gasket leak, I replaced mine almost 3yrs ago with an aftermarket Hitachi. Fortunately, I caught it in time so I had no electrical issues with the IACV motor and ECM being affected. Since you have the new one in-hand, when you have nothing better to do than play with your engine, go ahead and replace it. Don't forget to preform the IACV relearn procedure after replacing it. The procedure is written out in the factory service manual, starting on page EC-57. https://www.nicoclub.com/service-manual ... System.pdf

Congratulations on finding such a low mileage example! If it's running fine with no issues I would leave it be. That said, the only potential problem area with the IACV I've heard of is the possibility of the coolant lines into the throttle body leaking, which can allow coolant to drip onto the IACV stepper motor and eventually short it out. If that happens it will take the ECU down with it. Have you thoroughly inspected all the components and verified that everything is within spec? No leaks anywhere? When you purchased the IACV from Rock Auto I hope you were able to get the Hitachi OEM unit. If you plan on doing your own servicing make sure you've downloaded the service manual here. You'll need it - especially if you decide to do the IACV replacement. The dealer probably doesn't do a lot of those repairs because the vehicles that typically would need them are now over 20 years old or already out of service.

Thank you both for those responses and for sharing the FSM link.

Got lucky in finding the lower mileage was hoping for under 100k but they are like hens teeth. I went forward with the purchase as seems remarkably well cared and was a 1 owner truck. I was able to snag a few of the service details on the vehicle and found it was well serviced. I am not experiencing issues with the idle or leaks but I cant tell you how paranoid I was on the 350mi ride home watching the dash for the CEL.

Yes it was the Hitachi i bought after reading some posts on this forum and II watched a few videos on the effort. I do not see any leaks or feel any wetness around the area so maybe ill tackle when the weather improves as a fall project.

@mdmellott - was your leak easily visible? I have used mirrors, stuffed paper towels used my fingers and cant detect a thing but maybe am looking in the wrong area. I see the IACV but not 100% where a leak woulld be evident.

Next on my list is determining if the Power Valve screw threadlocker PM is also worth the squeeze. Thats a bit more a stretch for me.

01QX420147 wrote: ↑

Wed Aug 30, 2023 9:58 am

@mdmellott - was your leak easily visible? I have used mirrors, stuffed paper towels used my fingers and cant detect a thing but maybe am looking in the wrong area. I see the IACV but not 100% where a leak woulld be evident.

I had no leaking to the outside so there was no visible indication that was my problem, when I first looked. The o-ring-like gasket separates chambers in the aluminum body of the IACV assembly. The inside portions of the gasket started to fail so small amounts of coolant was getting sucked into the air intake which was causing my ignition spark to get hosed off, so to speak. That caused an occasional misfire, CEL would come on but then it would turn off. Scratched my head over this for quite some time until it got real bad and more frequent. I started to suspect the gasket to be the issue but still saw no wetness from any leakage on the outside. However, at the flange joint where it mounts to the throttle body I was able to see a dry, crusty looking, greenish line of coolant residue. It never dripped on the outside but there was enough evidence now to know for sure the IACV assembly had to be replaced.

@mdmellott - TY you have nudged me forward for the preventative repair. Ill review for the relearn procedure.