P0505 2001 Maxima

A few months ago I was working on a 2001 Maxima with the same PO505 trouble code which pertains to the idle air control system. The engine idle would not drop below 1500 rpm's even when the engine was at full operating temperature. I used a Nissan Consult II tester to check the operation of the idle air control valve and it failed the test. The valve would not change position and the idle speed would not change. Rather than spending the time to test the wiring to the idle air control valve I just installed a new valve. With the new valve I was still unable to get the valve to respond during a test with my Consult tester. I tested the wiring for continuity and all was fine. I figured that there must have been a problem with the cars computer so I removed the computer, pulled off the covers and inspected the circuit board. I found a burnt section on the circuit board and traced it to the terminals that control the idle air control system. I installed a new Nissan computer and left the new idle air control valve in as well. I didn't want to take a chance of putting the old idle control valve back in because it could have caused the problem with the old computer. The car would not start with the new computer until I programmed the keys to the new computer, then I had to perform an idle learn procedure for the idle to function normally. The car has been fine ever since. I hope this helps. Oh, and I also had the same problem on another 01 Maxima about a month ago. Had to do the same repair on that one as well.

Thanks for the reply. Initial symptoms - erratic idle then no idle. I read the code, purchased a IACV and installed it. Now the car would idle but @1500 and randomly rev to ~1800. I performed the manual idle learn procedure (conflicting stories if that works on the 2001) and it wasn't successful. After lots of research I decided that I needed to go to a shop with a Consult II tester, unfortunetly only the dealership has one in N. San Diego. The dealership was a joke. There was another 2001 there with the same P0505 and same symptoms that they had been trying to repair for 2 days. The service manager called me in and said that they spoke with some Nissan specialist and they were looking at the Electronic motor mounts because he had seen this fry the ECU with the P0505 before and it would be $2100. New IACV, ECU and both motor mounts. I showed him the wiring diagram I had and asked to have the tech and specialist explain to me how this could happen since they only share a relay and not the same contacts, how did they prove the ECU was bad and reminded him the IACV was new. Also I asked what the odds of both of mine and the other 2001s electronic motor mounts failing at the same time. They had just compared the resistance value with an off the shelf one and didn't isolate it from the system. They tested good the next day with Cosult II and they told me the ECU was confirmed bad (Covered by CA emission 8\80K luckily). They ordered it and a week later it still isn't in so I am not sure of the end result yet. Where did you get the Consult II from? They are $5-7K aren't they? Thanks again.

I'm not sure why the dealer is suggesting the motor mounts. I have not investigated that as a possible cause and have not found a reason to. I run a small auto repair shop and specialize in Nissan repairs. That's why I bought the Consult II tester, I also have the Consult I. I previously worked at a Nissan dealer for around 10yrs. I'm sure there are a lot of possible causes for the PO505 code but the only thing I've seen so far is the burnt computer circuit board and the only complaint on these cars was an idle control problem. Perhaps Nissan doesn't yet know why this problem occurs?? The second car that I serviced with the idle problem was previously at a Nissan dealer and they worked on the problem on and off for a month and could not figure it out. A new computer and IACV solved that car as well. I didn't put motor mounts in either of those vehicles and they're fine now. I'll have to look into the motor mount circuit to see if there is a possible connection, but I doubt it. I've replaced faulty motor mounts on other Maximas before and there were no other problems besides the mounts. I won't rule it out though since I'm not 100% sure. Keep us informed of your progress!!

The dealer called and said that the ECU was in and that they were suggesting I replace the IACV, Electronic motor mounts and the ECU. I declined the first two since I had just put in the IACV and I didn't believe that the mounts had anything to do with it. I picked up my car and they noted on the work request that I declined two of the three part replacements but the ECU was fully covered by CA emmisions warrenty,(thanks to the enviornmentalist). The car runs fine but I have noticed a couple times when I first start it that it sounds like the interior fan is making a sound like it is rubbing. If I turn off the interior controls it goes away and doesn't return when I restart it. It is probably in my head since I didn't drive the car for a week and a half. Anyway that is the story of my IACV and ECU trouble. Thanks to all that have provided information on this and so many other topics. DB

Thanks for the update. I wish everyone would take the time to let others know the final outcome. As far as the blower fan goes, I have heard that noise on a lot of Maxima blower fans especially on the lower 2 speeds. If the noise is loud there may be a piece of debris like a leaf or something like that in the blower housing which can cause a rubbing or fluttering sound when the fan is on. Discover more Honda Fit OBD Dodge I believe the fan noise is more likely from the electrical contact brushes in the fan motor making contact with the armature and creating the rubbing sound as the fan spins. As I mentioned I have heard it on a lot of Maximas as well as other models of Nissans. You may find a plastic insulated cover secured to the bottom of the blower which is suppose to help reduce the noise, but as you can see it doesn't always stop the noise. It's nice to know that your idle problem is solved. I'm still a bit baffled about the motor mounts. I've worked on a few Maximas where the electric mounts would make a buzzing sound for a few seconds after the engine was turned off and replacement of the mounts solved the problem however, I have yet to see the mounts cause a problem with the computer creating an idle control problem. The electric mounts are controlled by the computer but I still can't find the problems to coincide. Happy motoring!!

Thanks for the response. I'll have to take a look at it this weekend. I haven't looked into it yet but do you know if the 01 Maxima has a interior filter? Do you also go on maxima.org? I found that to be a very informative forum as well. Thanks again. What part of MA are you in? I was just out there a month ago for work in Andover. Nice place to visit but I got tired of the cold in Denver growing up. So. CA is nice this time of year. Take Care, DB

The 2001 Maxima is suppose to have a cabin filter. If it does you will need to remove the glove box and surrounding panel to access it. As far as forums go, this is the only one I visit. I stumbled across this site recently and just like to check it out once in a while. I'm located in Southern Mass. about half way between Boston & Cape cod. Andover is north of Boston. Enjoy Sunny Cal.!!

I also have 2001 Maxima GXE with the P0505 issue. I have replaced the ECM, the IACV, the motor mounts, the cam position sensor (what that had to do with anything is a question) and had the idle relearn performed. The light returned. It seems to have problems on start-up, but after that is runs well. Any ideas? Up to $2000 at this point. Keep thinking it can't take much more to get it repaired, but I may be wrong!

What code(s) are you getting now? Also, what kind of problem do you have on start up? Does it stall out, crank slowly, crank too long befroe starting? Additional information would be helpful. Thanks

I am still getting the P0505 code. Note that the MAF has also been replaced and the throttle body was removed and cleaned, then a cleaner was sent through the system. ba

Based on the info you supplied and assuming you used a New factory Nissan part when you changed the IAC valve, I would suggest that you try another New IAC valve and run through the volume learn procedure after the IAC is replaced. Make sure the entire IAC assy is replaced not just the electrical part. If a Nissan dealer originally replaced the IAC and it has been less than 12 months or 12,000 miles they should be able to replace it under warranty. The reason I suggest this is because a few of months ago I had the same problem on a 2001 Maxima that I was working on. I had replaced the IAC and the ECM with new Nissan parts, reprogrammed the keys and did the volume learn procedure. A short time later the same problem occured and the PO505 code was back. It turned out that the NEW IAC was bad and shorted out the new computer. The Nissan dealer exchanged the parts under warranty and I went through the same replacement process. The car has been fine for months now. It's worth looking into. Good Luck

chasr212r wrote: A few months ago I was working on a 2001 Maxima with the same PO505 trouble code which pertains to the idle air control system. The engine idle would not drop below 1500 rpm's even when the engine was at full operating temperature. I used a Nissan Consult II tester to check the operation of the idle air control valve and it failed the test. The valve would not change position and the idle speed would not change. Rather than spending the time to test the wiring to the idle air control valve I just installed a new valve. With the new valve I was still unable to get the valve to respond during a test with my Consult tester. I tested the wiring for continuity and all was fine. I figured that there must have been a problem with the cars computer so I removed the computer, pulled off the covers and inspected the circuit board. I found a burnt section on the circuit board and traced it to the terminals that control the idle air control system. I installed a new Nissan computer and left the new idle air control valve in as well. I didn't want to take a chance of putting the old idle control valve back in because it could have caused the problem with the old computer. The car would not start with the new computer until I programmed the keys to the new computer, then I had to perform an idle learn procedure for the idle to function normally. The car has been fine ever since. I hope this helps. Oh, and I also had the same problem on another 01 Maxima about a month ago. Had to do the same repair on that one as well. I am having this exact situation (high idle, replaced IACV) but the dealership tells me it is in the wiring and want a blank check to trace it. You said you "checked the wiring for continuity and all was fine" how can I do this? I have a multi-meter and know how to use it but don't have wiring diagram. Thanks, Jon

I have a 2001 Nissan MaximA 20th anniversary edition. I have never had any issues until recently. I first noticed the check engine light was on but nothing seemed wrong. In June I took it to my mechanic who told me the throttle position sensor was bad. Replaced that but it was idling very high. Took it back and he replaced the computer and idle air control. Six months later no luck. I've had it for a total of a week during this time. When I'm driving it it almost feels like it's grinding. I love my car and I don't want to "put her down" but I'm at my wits end with this and so is my wallet. HELP!!!!!!!!!!!!!

2001 Maxima SE Anniversary - I have the same issue - dealer said engine mount shorted, causing the IAC valve to short, possibly damaging the ECM. Said to replace IAC valve ($667), engine mount ($620) and possibly ECM computer ($1,400) if it is fried from the failure... can anyone tell me if there is another cheaper option?

3.5l....? start a new thread, list all codes. describe all issues, adding onto a 6month old issue not going to get a lot of eyes on thhis always get a second opinion.