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Thanks for the comment, hope you found some useful info in the video. With regards to your problem, the exhaust solenoid is shared by front and back, so I would expect issues with the front as well if it was that. I'd lean towards your used height sensors giving out. Good luck with the fix 👍

I am not familiar with the Century system, so I can only guess. Is it possible that the compressor shuts off when the doors are opened? Perhaps you have a leak, which is making the compressor run for longer than it should, and it is only just keeping up with the air being lost by a leak?

@@LS430VIP Thank you for replying. I have the car sitting in my garage for a week and it hold air 100%, it did not even lower 1mm. But as soon as I open the rear door, the air comes out very quickly, I can hear the air blowing out from the rear of the car.

@@Zi_life_cars a very strange fault. Sorry, I don't know enough about the Century system to advise why that might happen.

I'd definitely check the compressor connections first, or it could be faulty. You could also check the connectors to the air suspension ECU behind the glovebox, although I suspect that is connected as the buttons work as you mentioned. You won't see a lot of faults on the dashboard, a scan with Techstream would help see what is working and not.

@@LS430VIP I did a bit more troubleshooting. I checked conductivity of both of the air suspension fuses, which were good. I managed to get to the compressor, which was still connected. I unplugged it, and there is a much thicker wire in the connector, which I assume is the 12V. I never read more that 300 millivolts on it. Next, I pulled the air suspension relay, and I read 3.5-3.8V across the smaller terminals, but basically zero across the larger terminals, assuming they should be12V. I played around some more, and plugged the compressor back in. At that point, I was able to read 12V across the larger relay terminals. I assume there's some kind of fail-safe that if the compressor is disconnected, it won't request the 12V anymore. As plugging and unplugging yields that kind of change in the high relay voltage, I assume that means the remaining connections are good, and it is a dead compressor.

@@plamenpetkov5723 having the 12v om the big wires but no compressor does strongly point to a broken compressor. Also, I assume you are testing with the engine turned on?

No lubricant is needed, you should check that everything has been installed and tightened properly.

Hard to diagnose over the internet. If the compressor is running when the car is running but car is not raising, suspect a strut leak. If compressor is not running, suspect a height sensor.

Big leak or broken height sensor.

The 430 will actually air down slightly at highway speeds to improve aerodynamics, and air up again when you slow back down to town speeds, so it's normal for the compressor to kick in at stop lights etc. in those circumstances. It should be hard to hear though, I suspect you just need to replace the little bushes that hold the compressor on to quieten it down (part number in description).

@@LS430VIPSorry I forgot to mention. It’s usually after a few minutes after a cold start in the morning, after approx 15 hours resting. Compressor does not kick in right after starting, but after a few minutes when I reach a stop light, engine is still cold though. Happens usually once a week. The compressor itself is pretty hard to hear, but I can feel it slightly in the brake pedal at stop sign. Can this be considered normal behavior?

@@ThePerfectionOfLexus sounds normal to me. Again with the vibration, I'd consider replacing the bushings, but honestly it's not a big deal to leave them alone.

Honestly I wouldn't recommend running with no air, it's likely to really screw with your traction in corner bumps. I'd recommend getting an air suspension data controller, it will allow you to set the height however you want and raise and lower it.

There are aftermarket air struts that are designed to be a drop in replacement, they should be fine.

If the leak is large enough, the compressor won't be able to keep up with the amount of air lost so yeah it would stay low. I'd check the rear struts and distribution block with soapy water and for rips on the bags. Also, read the comments on here, loads of commenters have had issues with rear leaks so it's been covered before in my replies. Lot of useful info in the comments.

Just saw the fault finding segment. I guess the struts need to change.

@@sahibgaba1 it's possible. Also check for play in the bottom suspension arm rear mount, as that is a common bush to fail and can cause knocking.

​@@LS430VIP thank you for your help. You truly put out a great video. So the bottom suspension arm rear mount connects to the wheel and the rest of the car. When I put WD-40 on the part that connects to the rest of the car, I think that's when the squeaking pretty much stopped. Knocking still exists however. Could be multiple things failing but I will check it out tomorrow, and I'm hoping its just the bushing. I'm guessing I'd have to take it apart to really figure out what's wrong if there's no visible damage. The previous owner had the front struts and all control arms replaced 1.5 years ago, so all of these issues are coming in as a huge surprise.

I think those codes are set if you don't switch the height switches (High and Sport) on and off during scanning, they just allow you to test the switch. I doubt they are the issue. I would advise you to get the car scanned on Techstream to check the live height sensor values.

Glad to help. Part number for the compressor bushings ( that usually stop the rattle) are in the description.

Without physically inspecting the car I cannot say for certain. I would advise you to view the video and draw your own conclusions. I would start by inspecting the rear height sensors, and checking for large leaks at the rear distribution solenoid (if the difference in height is very large and you have no suspension travel on the rear remaining). If it is only slightly lower (maybe 30mm or less difference than the front), then the rear sensors probably just need adjustment. It is also possible that both rear bags have failed, but less likely than the other options. Again, I cannot diagnose this without the car present. Either use the knowledge in this video to diagnose the problem yourself, or take the car to a professional.

Thanks for the swift response. It is 30mm or less.

@@dr.ahsanhussain4382 probably the adjuster on the arm of the rear suspension sensor has slipped down a little in the slot, it will need to be undone and moved back up to centre of the slot.

The car is 18 years old. Problems are inevitable. It's the same amount of worry as a spring and shock on a regular vehicle, after 18 years a blown shock or snapped spring will happen eventually. You shouldn't expect a car that old to have no issues, but the air suspension is no worse than any other part, it's just poorly understood.

@@LS430VIP that is exactly what I wanted to know. I appreciate you to the fullest. Wanted to know if they are as reliable as springs. Should've just said it that way. Thanks again..

@ls430vip ok, one more for ya. Base model or loaded? Are one of them more reliable. I understand there is more to go wrong in the elite. I guess I just answered my question. I I'm the middle of 2 cars. One is a base for 8k the other an elite for 11500. Both are in great condition. The elite is priced a few grand over but it's so clean. The base i can get for a few grand under value. I guess i answered my own question again. . I'm lost. Haha don't want to make another bad decision. I'm so tired of bad decisions.

It's possible, one or both broken. The damage may or may not be obvious, I'd start with a physical look at them for breakage, and after that get the car scanned with Techstream to read the sensor values.

Thank you very helpful

Most likely a broken height sensor.

The compressor will not come on if the ECM thinks the car is already at the correct height. Ideally you should scan the car with Techstream to check what height readings it is seeing and for fault codes on the compressor circuit. A faulty compressor would seem most likely if you have checked the main compresspr fuse in the engine bay, but it is possible to be that the system simply thinks it doesn't need to turn on the compressor. You could bench test the compressor when removed from the car, off the top of my head I think it has two large wires for battery supply, and a couple of trigger wires. I recommend getting a wiring diagram and Techstream, or a cheap secondhand compressor to test with

Thanks for the advice ! I'll check it out.

Thanks for your kind words, and I hope the video helped

If you have run the car with the wheels off the ground or the sensors disconnected then the car may have disabled the system as a failsafe. If so, it will reset eventually, or disconnecting the battery for a few minutes may force a reset. If it doesn't reset, you will need to scan the car with Techstream to see if one of the sensors is malfunctioning.

Lexus do not mention it on the service schedule. I would only change it if you are in a very dusty environment (desert etc.) It is a small box near the compressor behind the front bumper.

Not really any way to test for certain as you'd have to rig up some sort of high pressure test rig for the valve and monitor for pressure drop over days. I think for 430 the valves were about £150 from Amayama, so not insanely expensive for a genuine Toyota/Lexus part.

@@LS430VIP thanks for a super quick response. So I'm gathering you feel this might be a reasonable thought as to the failure I'm experiencing. I'm going to be ordering some gaskets soon and will just include one of the valves. Massive thanks to you.

@@keithwood3783 yes it seems the most likely point of failure, if as you say the pipework and shocks have been tested with soap.

They're a bit fiddly to remove for sure. First pinch together the outer (pale white plastic) connector and slide it away up the line. Now the inner part is the tricky part, there are two barbs holding the line in. Some people use two screwdrivers to lever them out of the way but I don't recommend that as you can damage plastic parts. I instead cut a small piece of plastic pipe about 1-2" (25-50mm) that would be large enough to fit over the air line, then cut a small slit down the side of it so it can be inserted over the air line. Then slide it down into the strut connector pushing it in hard and it will push the barbs apart and the line will release. If you don't have a piece of stiff plastic pipe in the right size, I've even used a pen before cut up.

Yes you can swap in the entire struts (spring plus damper) on all four corners to convert your car to non-air. You must do all four, you cannot do one or two corners. You will need to also remove the main air compressor fuse from the fuse box in the engine bay to prevent errors (and the compressor from constantly running).

No worries!

I'm not sure I understand all your questions but: If your compressor is noisy then you probably just need to change the three mounting bushings on it. I've not tried the spring version but I hear that the ride comfort is almost identical. If you don't have air suspension already I really wouldn't bother adding it, as you will also need every single item shown in the video (ECM, actuators, switches, compressor and so on). You will also need a lot of the tubes that connect everything, it will be a difficult job to do. It will not make the comfort much better than springs. If you do not install absolutely everything, then the bags will be flat and it will be as if you have four flat tyres, the ride quality will be unbearably bad.

@@LS430VIP im not installing the whole system from ground up, the car apparently was already on bags from the factory, but the previous owner changed it to coils. So all what im gonna do is, get 4 air suspension and hook them.

@@K0J0K I see. As long as the other components are still working, then it should be possible, hopefully the previous owner did not cut the hoses to remove the suspension. The compressor may also be damaged if it has run constantly (they could have removed the fuse for it to disable it).

@@LS430VIP so after knowing the whole situation, what’s ur recommendation?

@@K0J0K inspect the whole system and see if it is all intact would be my recommendation.

Smaller than 1/8" I think, they are tiny. They will almost certainly be metric

If the compressor is running (while engine is on) and that side has dropped, that indicates a large air leak that the car is trying to pump back up, check for leaks carefully. If the compressor is NOT running, that indicates that the car has received a bad reading from one of the height sensors and thinks it is level when it is not. Test height sensors and replace the faulty one.

@@LS430VIP Thank you for taking the time to answer my question! I will be checking it in morning. I hope Techstream will help me with this problem.

@@LS430VIP You were right. Techstream gave me C1726 for LF sensor and C1751 for the air compressor running often. I will replace the sensor and hope for the best. Thanks again for your help!

@@bradata111 glad to hear it, Techstream is such a help for diagnosis

The leak must be there somewhere, sometimes they can be very hard to find. If you still can't find it and the solenoid or struts are available secondhand then I would replace them one at a time. Personally I'd start with the driver's strut, but you could make an argument that the solenoid is the common point too

Wonder if something to do with the automatic lowering at speed. When it tells.the suspension to rise again the front right let's all the air out.

Just to add no error codes show

Hard to diagnose, but the lowering at speed does seem to be triggering it. If it returns to normal after a while, and does not deflate when left for a few days, a bag leak is unlikely. Possibly sensor fault (bad reading at one part of the sweep of the sensor), or front solenoid fault. Tempting to replace those two with good secondhand units. Unfortunately an inconsistent error like this, with no codes, is hard to give a definitive answer to. The Lexus manuals do have a bench-test procedure for height sensors, which would show up any odd behaviour.

Ok thanks. Yes Lexus are struggling. Would the solenoid affect both sides? Is there anyway to cancel the lowering at speed?

Presumably its the ECM that controls the lowering could it just tell one corner something different to the others?

As far as I can tell, this is the over-pressure relief hose, if the pressure in the system exceeds what the compressor can handle then I think it will blow by the compressor piston and exit this pipe. I'm not 100% positive on that though, it isn't documented in the factory manuals, I think it just connects to the little filter near the thicker input hose. An over-pressure scenario could happen if for example you entirely filled the car with concrete blocks, far exceeding the load capacity of the vehicle. The suspension would try to level out but the pressures in the system would get dangerously high without a relief system. The manual mentioned a relief pressure of 142 psi, and that it will throw a code in that scenario, but it detects that code based on the compressor running for too long, there is no sensor for pressure so it's likely a simple blow-by system, the ECM does not get a PSI reading, only height readings.

Assuming you have not badly adjusted the sensors (and none are physically bent/broken), this points to one or more sensors giving bad reading. The best solution would be to scan the car with Techstream to see what the live readings from each sensor are, and then replace the bad one.

@@LS430VIP That’s a great help. Thank you so much.

You're probably overthinking this. The change with sport mode is pretty subtle, you may not even notice it. "Sport" is a strong word for a LS430! The motors are also in locations well away from water and debris so are unlikely to fail.

@@LS430VIP Thank you! I've just tried this as you clearly know your stuff about the LS430 suspension, and I've just taken mine out for a drive to try out sport mode. It worked great - firmed up, not quite as floaty over the bumps, cornered with less roll, and it could be me, but the throttle response also felt a bit more keen. As in, no extra outright power of course, but it seemed to want to give extra grunt more willingly at lower revs. Thanks for your help, hope you release some more LS430 videos in the future! 👍

Factory setting on the rear is to set the bolt on the bottom of the arm to the middle of the slot on the suspension arm. On the front, the factory setting is roughly 92mm of exposed skinny shaft between the locking nuts on the arms.

Wow thanks! I'm guessing you are a master-tech at Lexus?

@@3452dtn haha no, just spend way too much time tweaking my own car, and I write everything down before I change things!

@@LS430VIP Well thanks so much for your help. Lovely to chat to a fellow geek!

I would suspect the strut, I would change that first, it is an easy job on the front.

@@LS430VIP I thought so, just wanted a second opinion to confirm. Thanks man

Why would it be ok in high but drop in normal?

@@daviderhardt1496 I suspect the OP has the issue both times, it just takes longer to manifest when there is more air in there to leak out. I really can't diagnose your vehicle any more, I cannot physically inspect it so any advice I have given is best guess based on your interpretation of the symptoms. if your mechanic cannot find the issue, you can either take it to another one, or replace the strut and solenoid valve. Used ones are not expensive (relative to the labour costs), it may be best to stop thinking and start doing.

I don't know the 400 that well but you can ask questions on here

I'm afraid it could be many things, you will have to investigate it yourself.

The mounts on them are not the same so they are not interchangeable. You may be able to cobble something together to make them work but they are not bolt-in compatible. I think also the front one has an extra port for the pass-through to the rear.

Most likely a loss of damping (shock absorber) on one or more of the shocks. Inspect for fluid leakage down the shock or at the top mount. You can also perform the usual bounce test on each corner of the car to check it settles back correctly and doesn't continue bouncing. Replace any failed shocks, they are not serviceable.

Thanks for your response... I will check that out. It seems odd that the shocks would go bad for only having 50,000 miles on the car... being these shocks cost around $2,500 per shock.

@@johnkanduit2144 True, although you have to remember that these cars are now 17-23 years old, and in that time parts will deteriorate. Rubber seals particularly will harden and become brittle with age, and that is somewhat unavoidable, even on a quality product.

If there is fluid escaping from the shocks then that is damper fluid, so that will explain the bounciness. Those shocks that are leaking will need to be replaced. I would start with that, as they will cause harsh ride and probably knocking too. You should also look at the bushes at the rear of the front lower arms. These can be seen by looking under the car behind the front wheel, they often wear out and cause clunking. Small height differences between corners are not unusual, all the height sensors have adjustment on them to tweak this.

@@LS430VIP brilliant, thank you that’s a great help