Hey Pete, just wanted to give you an update. Unfortunately my wife was fed up with the vehicle from not starting at the first try a couple of times to the suspension. She traded in her vehicle. Sorry I was unable to come up with the problem. It’s still a great car but she just wanted to upgrade. Thanks again for your help.

 

Does anybody know if the air compressor will run while driving? The Infiniti mechanic said it does not. Since weird.
Also I have put air bags in the rear coil spring on our QX56 and QX80 which helps when towing.

 

This doesn't make any sense and would defeat the purpose of the self leveling system. Below is the Air Levelizer Control System description.

"Based on the signal from the vehicle height sensor, the air levelizer control module operates the air compressor (exhaust solenoid) and controls vehicle height so that it remains at a constant height. This operation occurs if vehicle height of vehicle rear is judged to be 15 mm (0.59 in) or more or 15 mm (0.59 in) or less than standard vehicle height, continuously for 30 seconds, when engine is started."

In other words, once you start the "engine" the system will analyze the vehicle height for 30 sec before it activates the compressor or exhaust solenoid and adjusts the height if needed. In the description it says nothing that the vehicle needs to be stationary. Imagine the scenario that you load the vehicle, hook up a trailer, start the engine and start driving. If the system only operates when the vehicle is stationary it would rarely work, which makes no sense at all.

Interestingly, the system gets input from ABS actuator and electronic unit for vehicle speed but this is only used for detection of height sensor performance. It looks for a condition of no change in height (using the sensor voltage) for 100 hours of driving over 2km/hour . If this occurs it will flag a code C1806 indicating height sensor malfunction.

You can simply test it. Load the vehicle, start the engine, wait for the compressor to kick in and start driving...and you will hear it running until height is achieved. Mine would kick in all the time, while driving, and this is how I knew it started getting bad. It shouldn't really kick in when driving that often as this indicates a leak in the system.

 

Agreed, I think it would run while driving. When I was a towing a camper, I would get gas, start the car and the compressor would kick in to level the vehicle.
When I stopped again for gas, the car was sagging.
The dealership checked and no codes were logged indicating issues.

 

I would guess the compressor is wearing out and it developed small internal leak(s). When you load the vehicle with a heavy load/trailer it has to build up even higher pressure to level the vehicle and, due to these potential leaks, it cannot achieve the proper height within 120 seconds. Then it shuts down and will not activate anymore. As you continue driving the compressor continue leaking, as the heavy load keeps "pushing" on the air system and you keep losing the pressure until the rear just sits on the coil springs, without any assist from the air shocks. The compressor will not re-activate until you turn off the vehicle and restart it. I am not sure if the E-SUS module codes are stored. This could be the reason the dealership could not read the codes. If I had this situation I would hook up the Nissan code reader and monitor as I drive with the trailer. If your compressor is old I would start with replacing it. This is the most common culprit of all rear suspension leveling issues.

 

Thanks for the feedback. On our 2011 QX56 we had similar issues and the dealer was able to local the codes to determine what to replace.

So the compressor will only run 120 seconds and then stops whether or not the correct is achieved?

Again, thanks for the feedback.

 

There are a few conditions in which the air levelizer control module will go into fail-safe mode and will shut down the compressor. For instance If you "significantly" overload the vehicle, the compressor runs for 120 sec and is unable to achieve standard vehicle height position. Or if there is a leak, which it would result in pretty much the same condition. There is also cumulative operating time of the air compressor of no more than 180 seconds in one ignition cycle. Meaning that if you start driving, compressor runs for 90 seconds to set the height, but there is a leak and compressor needs to pump more air 3 more times for 30 sec, then it will shut down and will no longer restart until you turn the vehicle off and on.

 

I know many people have trouble diagnosing the suspension issues and dealers often don't find any codes. I am really wondering if the suspension codes are stored in E-SUS module, like engine or vehicle codes in respective modules, or if they are reset with every ignition cycle. I couldn't find this information anywhere so if anyone knows please share...

 

I want to confirm that codes are stored in the the E-SUS module. I just drove 21 hrs straight across the country, fully loaded through the roof and over the roof (large and heavy ski box), few times running engine 5+ hours before switching off, and I did find code C1808 stored. It was not active so it happened at some point of the trip. There was no suspension light on the dashboard. To find it you will need a dedicated scanner.

This code basically indicates that sometime during that trip the compressor run more than 180 seconds of cumulative time, between vehicle ignition cycles, reached that threshold and went into fail safe mode, by stopping the operation. I have a new compressor, new OEM shocks and everything is double checked so it was clearly an overload condition. And I knew I overloaded the vehicle even before checking the codes.

What was important is that I did not get C1806, which means the vehicle achieved the proper height at first, but then compressor activated again to pump more air after an hour or so, and then again and again until it reached that threshold of 180 seconds. The natural fix for this condition is to pull over at the rest stop or gas station and shut the vehicle down. This clears the cumulative time condition.

 

Thank you OP for the write up. Very informative. I have seen quite a few of these QX80s with the rear sag and always wondered what was going on. I figured there might be a heavy load in the back.

 

Hello, Pete I own a 2019 qx80. I only start having this problem after my warranty was off. So I went back to to the dealership where it happened.My husband work on cars and he check all those things He said , this vehicle is too new to have this problem with only 45,000 miles.While having my husband on the phone the salesman came and said, the only thing you probably needed is to bring your vehicle back in to be hook up to the computer to be reset to the height. My email is vgtnth@yahoo.com.

 

Only on 1 side.

 

Yep. There is only one height sensor that controls the rear height. This is why most have some difference between left and rear wheel which cannot be easily corrected. I have about 1/4" ~ 1/2" difference on both of my vehicles. You would never know until you measure it though...

 

i do not want to come across that, but in the even that it does happen. What is the maintenance required to fix the problem?

 

Not sure I understand the question exactly. There is no maintenance schedule for the rear suspension air leveling compressor. When it dies it needs to be replaced. Like with many other components its life is determined by number of cycles, operating time and environment that it operates in. What kills the compressor overtime is internal leakage caused by parts wear. Parts wear can be accelerated by driving on dusty roads or in winter, on wet, salty roads. Its sits pretty low to the ground so it will suck all the air that flows around there. The intake tube inlet is inside the frame to reduce the dusty and salty air getting into the intake. It also has some pretty low quality filter/screen which probably doesn't do much. The only thing I can think of is to wait one minute after you start the vehicle so the compressor will finish the leveling cycle before you drive so this way you will minimize sucking the dusty or salty moist air kicked by the tires, but honestly this seems not very practical.

 

hi my qx80 when pass couple hour stop .i have a differance 3/4 fromm then other side ?? its my ajusting levelling ? the garage just change the sub frame on it

 

When you start the car does it level out,it should level as the pump inflates the shocks air bags.When parked mine goes all the way down and rises up when I start the car

 

Hi all, not sure if this thread is still alive but hoping so... (2019 QX80 here)
I had a small pinhole leak in the rear passenger shock, the rubber part, and after starting the car the compressor would run to fill it up. Not a huge deal, but decided to replace that shock.
My buddy with a small shop suggested an aftermarket shock which was significantly cheaper (regretting this) and replaced it. I was on a work trip so didn't get to see the work get done.

Fast forward, it's been about 3+ weeks since install and the ride is so bouncy. Feels like I'm driving a trampoline sometimes on the back. The front suspension, which wasn't touched, now feels very hard and going over even small bumps I can feel 'clanking' (like suspension joints are loose or perhaps the shocks are set to too high pressure and there is no cushion).

Reading your write up, I'm wondering if the mech didn't measure shock height before torquing the bolts, or if somehow the ride height is now higher than it used to be (maybe pressure inside shocks is too high?)

Any thoughts? Or could it just be these aftermarket shocks and I need to just buy OEM and reinstall?

Thank you in advance

 

Did he just replace one shock? If so, this is a big miss. You should never ever replace one shock especially if you went with a non OEM shock. Even with the OEMs, shocks wear out and damping characteristics change over time so if you have any mileage on a vehicle you have to replace in pairs. What brand did he use? Even if it physically fits it doesn't mean it it will match damping characteristics of the whole vehicle. Ride and handling is a science and your friendly Nissan Ride Engineers spend 3 years tunning Tokico shocks for their best performance. You cannot just put any one shock and assume you you will match damping characteristics of the one you removed. (I am assuming here that compression and rebound travel of this "new" shock matches the OEM one.)

If you go non OEM you need to find a reputable company (Sachs, Bilstein, KYB, BWI, Monroe etc) that will "try" to match your original Tokico shock performance and always replace in pairs.

If you care about you vehicle ride and handling (which affects safety) I would bite a bullet and replace what was installed. I would just put two new OEM shocks. its $500. Find the cheapest Infiniti dealer online and have it shipped to you. And since the vehicle is not that old you could keep the mounts (although I would personally replace them...its $100). And if you ask "your friend" to do it please make sure he torques lower bushings and top mounts with vehicle on the ground or with wheels lifted in the design position not hanging down on the shocks. This is a common mistake.

I would not mess with the front suspension. If the problem wasn't there before it's not there now. Correct the rear and then re-assess.

 

2016 qx80 here. I have pretty serious sag in the rear. I took it to a nissan dealership as the nearest infiniti one is quite far from me. After 2 days and 2 diagnostic fees, they determined the compressor is good (replaced in October 2024), but the left sensor is not working. They ordered in an aftermarket sensor for $600 CAD (OEM was $1400+), but after testing, only the right side was working. They now believe I need to replace the module and quoted me just over $3,000 CAD for the OEM one. They couldn't locate any aftermarket modules, but managed to find a used one they could bring in from another province for around $800. At this point I'm starting to feel like this is going to be a chronic issue. Any advice what to do here? Is it worth my time to go to the INFINITI dealership (1 hr drive away). Diagnostic fees at just under $200 per hour are bleeding me dry. I contacted a strut/suspension specialist shop in my area and they would be willing to assist with a converting to coil springs if I choose to go that route

 

If this really a suspension module than it gets expensive. And you are stuck with the dealer as they need to re-program the module and set up the height properly. You need CONSULT for this. Its get complicated.

You could do a conversion in that case. Especially that you will need new shocks anyway. They are close to 10 years old. So I would consider this option for sure.

It really depends what is the condition of your vehicle and what you want out of it. If it is pristine and you want to keep everything OEM and perfect, then you will need to spend $$$. If you feel you just need a car that drives and don't care it needs to be OEM than save money and do the conversion.

 

If this really a suspension module than it gets expensive. And you are stuck with the dealer as they need to re-program the module and set up the height properly. You need CONSULT for this. Its get complicated.

You could do a conversion in that case. Especially that you will need new shocks anyway. They are close to 10 years old. So I would consider this option for sure.

It really depends what is the condition of your vehicle and what you want out of it. If it is pristine and you want to keep everything OEM and perfect, then you will need to spend $$$. If you feel you just need a car that drives and don't care it needs to be OEM than save money and do the conversion.

Hey Pete, thank you for the response and recommendation. I can confirm the vehicle is pristine in every way. Dealer-serviced since purchase and all recommended work done. Currently has 110k KM (68k Miles), and the mechanic said shocks are still in great shape. After I posted this I actually purchased a used module off eBay and the dealership says they’ll install it for me when it arrives. Cost me $125 US, so even with the labor cost it won’t set me back much and might just fix the issue. 🤞🏼

edit: I should add that the used piece had a grade A inspection mark and was taken from a 2020 qx with 50k miles, so hopefully will go for a spell without needing replacement.

 

Welp, a year after I posted in this thread…..the SAG has happened! It is noticeable. 2015 QX80 Limited, 86k on the clock. I could sometimes hear the compressor running but can’t hear it anymore. I drove it yesterday with my son, we took a route that had speed bumps and the ride over the speed bumps was very different. It felt like the truck was just resting on the rear springs. There was definitely no “bounce” or several bounces after driving over the speed bumps. I think the shocks may not be the culprit. Does the air leveling system effect ride or give a firmer ride?

 

Having just gone through this, I can say the difference between bumps with a working air suspension vs just the coil springs is significant. I was definitely not getting several bounces, it was very stiff feeling.

 

Hello I have a 2016 QX80, 114,000 miles I just had the front coil-overs replaced at the Dealership shortly after I noticed the rear sagging my poor truck but there wasn’t any codes visible on the dash. Soo, I took my generic Blue Driver Bluetooth obdll tool hooked it up had a code for ride height sensor, so I cleared it, and crawled under the truck started back probing the sensor, and yes it was getting signal power and ground after the connected, I unhooked the arm at the ball and slowly moved it, it started at like 4.7 volts and I could raise it all the up and it would start to go down but then climb back to 4.7 so yea it’s shot. So I order a cheap one off amazon 50 bucks pacewalker. Now I don’t know the procedure of replacing the sensor I just crawled under took the own off put the generic on plugged it in, oh yea I did unhook the negative battery terminal hooked it all back up wouldn’t come on the air compressor so after much research I bought the diagvcx nano for Nissan/ Infiniti and installed consult 3 plus v240.10 and that’s where I’m at now