After having read reviews and researched Hella TC-400 and Orange Electronic P409s kits, I decided on the P409s because it is less expensive, less complicated to install, displays 4 tire pressure readings simultaneously and has one small display unit (vs a display unit AND receiver that the TC-400 requires).
I installed the sensors myself onto brand new 18" BMW aluminum alloys and had my shop use a dial-type torque wrench to torque the valves (included in the kit) down to 4 newton meters (~35 inch pounds), exactly as the Orange Electronic P409s manual states. If you don't have a dial type torque wrench (not clicker), then you'll need one to install this kit. I then had them mount the tires on and as soon as they pressurized the tires, the sensors turned on.
The kit includes absolutely everything you need: valve cores, valve stems, valve stem caps that say (sensor inside), and sensors. The only thing you need are wheels and tires.
Finally, it takes about 5-10 seconds every time you plug the head unit in for the sensors to link up to the head unit. And the digital readout is very accurate, providing the identical reading that my handheld digital tire pressure gauge gives. What an awesome kit, from the cockpit of my BMW 850i (which has a lot of insulation, I was concerned about wireless reception), I can get the signals from all four sensors. There are no reception issues to report.
You can manually set the high and low (pressure and temp) alarm thresholds, and upon trigger of an alarm, the sensor in question lights up red on the display and it starts beeping. If you pressure the top button once you can silence the beeping. It's amazing to watch the tire pressures as you drive, you can watch them rise and see how high they really do go, this helps a lot because I use monitor my pressures closely to equate to the amount of grip I'm get during some of my performance drives on curvy country roads. Having this kit has allowed me to tweak my optimum cold tire pressures in order to properly balance tire life and grip.
I highly recommend this product, especially for high performance sports or luxury cars. In my humble opinion, the P409s is the way to go for after-market TPMS.
IMPORTANT NOTE: It is useful to note that when you buy the kit, if you plug in the head unit, the sensors will NOT LINK UP to the head unit UNTIL you install them and pressurize the tires. They have a sleep mode that goes into effect when there is no pressure in order to preserve battery life while the unit is sitting on a shelf. So if you buy the kit and want to "test" it prior to installing it with tires/air, it won't work until you actually pressurize the tires and then plug the head unit in.
I have found this to be the best of three different after-market TPMS that I've tried. This valve attachment location has proven more durable than the band technique. The simultanous four-time readout is more user-friendly than those readouts that require a button to be pushed repeatedly to change among multiple tires. This unit has proven appropriately sensitive to low tire pressures on multiple occasions. Economical. Highly recommended.
Buy Orange Electronic P409S Retrofit Tire Pressure Monitoring System Now
***EDIT May 2013***
This update comes about 5 months late, so I apologize. I am going to withdraw a virtually unconditional recommendation for THIS product. The rating is reduced to 2 1/2 stars (rounded to 3 for its merits) and recommend it only if the prospective buyer can be satisfied with a 3 to 3.5 year battery life tops. Longer life will just be a bonus. My experience effectively shows the useful life of the system to be only about 50% of of what you might expect from the stated battery life in the manual (7 years nominal). Others are reporting about the same in reviews after mine. The cost for replacment sensors plus installation and balancing costs puts it nearly out of the range of simply buying another TPMS system unless you can time the replacement with tire replacement. Once a single sensor begins to fail, the others will likely follow shortly behind.
In addition, it is virtually impossible to reach the company with the phone #s provided on their web site, although the site itself has improved for English speakers over the years. Interestingly, I was contacted by Orange about a year or so after my original review to contribute a testimonial for their product. I declined, stating that the material in my Amazon review pretty much wrapped up my experience with the product and they were welcome to use any of it.
I emailed them in November 2012 to see what could be done about battery life and to date there has been no response. A phone call today to the "company" was taken by an answering machine that identified (and verified) only the number I was calling...no company greeting, business hours, etc. There have been many reviews since mine alleging this system to be unsupported. Certainly, it would seem that my experience would seem to support that claim. Kind of sad because it is otherwise a great product.
ALSO NOTE: The USB cable supplied with the 409S is stated in the manual as not being compatible with standard USB devices. I suspect that is because the voltage it supplies to the receiver/display is 12 volts instead of 5 volts that phones, GPS systems, etc. use. Have not been able to verify that because it is really tight to try to measure even with removing the back of the display. So, if your 409S fails, don't try to use that cable on another USB device without verifying that voltage!!!
I am going to let stand that which was previously written below.
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...and highly recommended if you don't. Bought this device from another online vendor because Amazon had not yet started carrying it. This one gets only 4 1/2 stars because depending on where you place it, the display might not be readable in bright light conditions. However, the audible alarm will promptly alert you of anything headed south with your tire pressures.
(UPDATE Dec 04, 2011: As of this date, I still own this Subaru and have put an ADDITIONAL 100,000 miles on it since the failure of the center differential that was suspected of being caused by one chronically low tire over the first 80,000+ miles under the most extreme of driving conditions with no hint of the second differential encountering a similar issue.
While the potential consequences for damaging an expensive drive line component in an AWD system due to one low tire would appear to be arguable in theory as discussed by one knowledgeable commenter, the tolerances in today's AWD systems might just well call for tighter control of tire pressure conditions to prevent damage OVER THE LIFE of the AWD vehicle, especially in the seemingly superior AWD system of the Subaru. Is it possible that in less capable systems, AWD prowess is sacrificed for long term reliability of drive-line components? It's not worth it for you to find out the hard way.) END of UPDATE.
I bought this tire pressure monitoring system (TPMS) after losing the center differential to the tune of $880 in our 2004 Subaru. What in the world does this have to do with TPMS? Well, it turns out much more than you would think!
Most folks who own full time all wheel drive vehicles don't realize that they must keep close watch on tire pressures, tire brands, etc., especially if you have a manual transmission. If you own a full time all wheel drive vehicle, check your user manual to see what it says about buying tires for it and keeping
them properly inflated. Many of these vehicles might have to have ALL FOUR tires replaced in the event only 1 becomes unserviceable.
You might also find that you will have a FULL SIZED spare instead of one of those donut types. This is because no tire can vary in CIRCUMFERENCE more than 1/4" 1/2" from another in order to maintain proper rolling characteristics. That my friends, is a pretty tight spec! Pressures must also be adjusted for loading of the vehicle. Some all wheel drive vehicles might still have the donut spare, but you will be limited in speed and how far you can drive on it. Your user manual might not explain why or you might question it and ignore the precaution...a very bad idea. Failure to heed this tidbit of information could result in a very expensive repair. The forces at work here are similar to those of driveline binding, a concept known to most seasoned 4WD vehicle operators...it just never occured to me how much a chronically low tire on a drive axle could really cost me!
The reason for this can get a little technical but I will try to keep it simple. The amount of air pressure in most tires affects how many times it will rotate over a given distance. With less air pressure in your tire, it will generally roll more times per mile, run hotter and under certain conditions, put more stress on the driveline of your full time all wheel drive vehicle. If it is normal for your tire pressure to be 30 psi at all 4 wheels and you have one tire running at 22 psi, you could be headed for trouble if you allow this condition to persist. It is even worse if you have a slow leak and just keep pumping it up rather than getting it fixed like I did.
Most all wheel drive vehicles have some means to detect the rotation of your wheels and based on that information redistribute power to the wheels that have the most traction. One tire running substantially low on pressure than the other 3 will be seen as a wheel that is constantly slipping. Yourvehicle will try to compensate for that by sending more power to the other 3 wheels. Usually a differential of some sort is involved in that process. Under low speed conditions, say 5 mph or so, there is really not much of a problem. But if you run a tire that is chronically low for 5000 miles (an oil change interval) at highway speeds, you could be headed for trouble. The lesson here is that a low tire over thousands of miles on a drive axle could eventually cause a problem.
How fast things go downhill will likely be determined by the design of your all wheel drive vehicle, the power distribution concept, whether it is an automatic or manual transmission and the difference(s) in the rolling characteristics between wheels.
In 2008 I believe TPMS systems became mandatory on all new vehicles sold in the U.S., but that was mostly safety related to prevent accidents that could be attributed to poor tire inflation. There was probably a little bit of "green thinking" involved in there, too as tire pressure relates to fuel economy and its impact on the nation's oil reserves. Some of these OEM devices are reported to
be not as flexible as after market ones.
What I like about this model is that you can set the Hi and Lo alarm limits for your application. (OEM TPMS systems might not allow you this flexibility because they don't want you changing anything.) The Orange's display will show green for
tires within the limit and turn to red and sound an alarm when the pressure goes outside the limits. You can also set the device to show pressure only, temperature only, or to toggle between temperature and pressure as well as set a temperature alarm. It is also one of the easiest aftermarket devices I've seen to reset when you rotate your tires.
I had my system installed upon buying a new set of tires at a popular warehouse chain. They installed it at no additonal charge. You will have to learn how to set it after rotating tires as some tire shops might not know how to do it, especially if you didn't get the device from them. It is also a good idea when you buy new tires or have a tire removed from a rim for flat repair, that you
let them know you have such a system installed in order to prevent damage to the sensors. In the days of rubber valve stems, tire shops would cut the valve stem or use a tool to pull it out to deflate the tire faster. Any tire shop worth its salt should be able to immediately recognize that you have a TPMS by looking at your valve stem. This may cause some tire shops to want to at least provide a new internal spring loaded portion (core) of the valve stem when servicing your tire. I would expect the fit to be fairly universal with no issues. However, they should not try to sell you new sensors. If you need one, make sure it is from Orange to ensure compatibility wth your display. I really see no need to replace sensors unless they are not working. For what it's worth, I have driven millions of miles and have never had the core of a valve stem fail, although I have recently had the rubber type valve stem fail because of long term exposure to the southwestern elements and an improper material spec when manufactured on the other side of the Pacific.
One final note is that this device should be relied upon only to detect changes (mostly deflation) in tire pressures. You will get much greater accuracy and conistency of measurement using a simple slider type tire gauge. Electronic devices have random and systematic errors that can affect their accuracy even among the same types of sensors. Be mindful of the accuracy spec on the TPMS and that you are actually using a different sensor to measure each tire. If you see a difference between your tire gauge and the TPMS, most often the tire gauge will be more accurate. Use the tire gauge to set pressures and use your TPMS to detect and warn you of changes that can affect safety and help you avoid conditions that can affect the long term service life of your vehicle's drivetrain.
If you have just regular front wheel or rear wheel drive, this device could easily save you a lot of money just by preventing things like an expensive tire from being destroyed, being stranded in the hot desert with your wife and kids or something similar. I even carry a pump now in case I develop a slow leak. If you don't have TPMS and do a lot of driving....get one....THIS one!
Read Best Reviews of Orange Electronic P409S Retrofit Tire Pressure Monitoring System Here
Orange Electronics has closed up in USA and Europe. Asia is giving us vendors no support on warranty issues. If you buy this remember you are buying an unsupported product. Such a shame as it was a GREAT product too.
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This product might work well on passenger car tires but not on my pickup truck. I encountered 2 problems. First, the highest pressure That can be set for the over pressure alert is 60 psi. My truck tires are inflated to 70 psi so the alarm goes off and must be manually turned off every time I start the vehicle. The second problem is that with my crew cab truck the farthest tire from the unit (right rear tire) is too far to broadcast a strong enough signal to register. I thought maybe the sensor in that tire was malfunctioning but I switched the tires around and the right rear never gets a strong enough signal to register.
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The battery comes empty, with the acid in a separate six-compartment bottle. Pouring the acid in is fairly easy, but takes some time and you have to be able to read the instructions so it's not completely idiot-proof. So far it's been running very well.
