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Replacement Check Valve for Demco SBS Supplemental Braking Systems
(65 reviews)
Price: $27.14
In Stock
Demco
Replacement Check Valve for Demco SBS Supplemental Braking Systems
Part Number: SM99909
In Stock
$27.14
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- Reviews (65)
- Q & A (0)
- Videos (1)
- Photos
Demco Accessories and Parts - SM99909
- Flat Tow Brake System
- Valves
- Demco
Replaces the check valve that came with your Demco SBS Air Force One (SM99202 or SM99243) or Stay-IN-Play Duo supplemental braking system (SM99251).
Features:
- Replaces the check valve that came with your Demco SBS supplemental braking system
- Works with Air Force One (SM99202 or SM99243) and Stay-IN-Play Duo (SM99251)
- Check valve installs between the brake booster and the towed car's engine
- Required on all towed cars that don't have a diesel engine and aren't Hummers
- Includes 1 replacement check valve
16126 Demco SBS - (Formerly SMI) Replacement Check Valve for Air Force One or Stay-IN-Play Duo Supplemental Proportional Braking System
Replaces Demco SBS SM15601 and SM99909
Video of Replacement Check Valve for Demco SBS Supplemental Braking Systems
Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.
Video Transcript for Detailed Breakdown of the Replacement Check Valve for Demco SBS Supplemental Braking Systems
Hello, everybody. This is Jeff at etrailer.com. Today, we're gonna take a look at this replacement vacuum check valve for the Demco SBS Supplemental Braking Systems. This is for a quantity of one valve. Now, this part here replaces a vacuum check valve that came on your Demco SBS Supplemental Braking Systems. This is designed to work with the Air Force One system, part number SM99202 or part number SM99243, and also works on the Stay-IN-Play DUO, which is SM99251.
All three of those systems we do sell separately our website. Now, those systems use two check valves in the vacuum lines. One check valve will install between your brake booster and the tow car's engine, and the other one installs between the operating unit and the vacuum line. Now, these are required on all tow cars that don't have a diesel engine, and this part includes one replacement check valve. But that should do it for the review on the replacement vacuum check valve for the Demco SBS Supplemental Braking Systems.
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Customer Satisfaction Score:
98% were satisfied with this product
2% of customers were not satisfied
- Product did not meet expectations
- Wrong item was ordered
Ratings & Reviews
4.7
65 reviews
by:
Steve
06/10/2026
If you have had your system installed for 5 years like us, you should think about changing out check valves. The new redesigned check valves are more sturdy/substantial than the originals. One of the two check valves had failed,ie could see daylight when looking into end of valve. All warning lights cleared on dash and the vacuum pump quit it's erratic cycling.
by:
Steven
08/16/2024
I had read that this was an improved check valve for the air force one braking system. It is larger than the old one and appears more robust. I installed it and it is working like it should.
by:
Paul
09/22/2026
Easy to order the exact part I needed and it arrived quickly.
by:
Larry
07/16/2026
Great support!
by:
Charlie
07/03/2024
Unfortunately, I heard about the issue with the Air Force One brake systems check valves thru a forum. I had the tale tell sponginess in my brakes while driving. I ordered two of these to replace the ones provided by SMI. Of the two check valves...the one that is between the AF1 controller and the brake booster was shot...you could see light thru it. I replaced it with this new check valve and it made a huge difference. I only wish Demco/SMI would have sent notice to their customers to notify them of this.
The check valve does look more robust...however, while twisting a hose, I found the two halves do come apart rather easily. So, it might be worth your while to wrap some tape around the joint between the black and white halves...to prevent it from coming apart... never know when a technician will grab a hose to look at something else...and not notice the check valve separated.
The check valve does look more robust...however, while twisting a hose, I found the two halves do come apart rather easily. So, it might be worth your while to wrap some tape around the joint between the black and white halves...to prevent it from coming apart... never know when a technician will grab a hose to look at something else...and not notice the check valve separated.
by:
Tim
06/09/2022
Needed a check valve to install a braking device on Jeep when towing behind a Class C. Finding the part on the website was a bit challenging but, they had it. Ordering was simple and straightforward.
Tim
6/9/2023
Working great!!!
by:
Michael
01/10/2020
Exactly what I needed. Bought a used Invisi-Brake and needed a 3/8 check valve for the master cylinder. This part is perfect. Fast shipping and a great price!!
by:
Roger
05/13/2024
These are the latest design check valves from Demco, a direct replacement of the prior units. My valves were 5 years old, no issues, but I replaced them out of an abundance of caution, to avoid any issues down the road. Order was filled and shipped promptly, great service.
by:
Kevin
02/02/2023
First class service and very pleasant staff. I was advised of how things were progressing throughout the process right up to and including final delivery. Thank you very much.
by:
Guy
04/29/2021
Ordered this to have on hand in case it is needed. We had one go out on us & the manufacture replaced it under warranty. it is an easy fix if you have the part.
by:
David
12/29/2024
Fine replacement. Glad you had it and was well made.
by:
Ryan
08/22/2021
The part came quickly and was the correct part. I am very pleased with etrailer and will use them again.
by:
Olympia
02/15/2021
etrailer does a very good job for us in all areas
by:
Richard
09/16/2019
replaced a bad check valve after five years.
by:
Anthony
10/02/2022
Check valve was delivered promptly and fixed the problem I had with the old one.
by:
James
05/07/2021
Worked perfectly in my application.
James
5/7/2022
Still working flawlessly
by:
Patrick
04/09/2019
Came quickly and well priced
Patrick C.
4/10/2020
Perfect
by:
John
05/20/2024
Arrived super fast. E-trailer is the best
by:
Dan
03/16/2024
I ordered two one way check valves for an aux brake system. It was a good thing they arrived undamaged. They were not packaged individually and thrown into bag that could have been easily crushed with minimal weight. I am not happy about the length of time it took to receive the merchandise and how it was packed!
by:
donald
02/14/2025
On time and as described.
by:
John
01/18/2021
This product is exactly what I was looking for . Works as advertised. Prompt shipment
by:
James
05/14/2021
Worked perfectly in my application
by:
Daniel
03/10/2025
Not in package! Where is this item?
Brooke M.
3/10/2025
Sorry to hear that Daniel! Let me look into this for you. Be on the lookout for an email!
by:
Jim
01/08/2019
Fast, as ordered, pleasure to do business with.
by:
Billy B
12/20/2020
As advertised.
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See what our Experts say about this Demco Accessories and Parts
- Replacement Check Valve Needed For The Demco Air Force One Supplemental Braking System Hi Wayne, The Replacement Check Valve for Demco SBS Supplemental Braking Systems # SM99909 is what you're looking for. You'll want to place the black end towards the main unit of your Air Force One # DM23MV. If you need anything other replacements just let me know and I'd be happy to help.
view full answer... - Availability of Replacement Check Valve for Demco Air Force OneHey Michael! The Replacement Check Valve for Demco SBS Supplemental Braking Systems # SM99909 is what you need. This will replace the valve that failed on your # DM23MV. What kind of motorhome do you have?
view full answer... - Troubleshooting A Hard Brake Pedal After Flat Towing A Jeep With Demco Air Force One Based on the symptoms you're describing with your Air Force One # SM99243 it sound like you have a leak somewhere and the brake booster is having to rebuild the vacuum pressure, which is why the pedal is hard and requiring you to pump it back up before driving. I recommend looking at your check valve between the tee and engine for leaks and tracing your air lines for any cracks or loose connections. If none are found then the check valve could have also just failed and needs to be replaced...
view full answer... - Correct Replacement Check Valve for a Demco SBS Air Force OneYes, that is an indication that your check valve between the tee and operating unit has gone bad and is going to need to be replaced. To replace it, you'll just need the Replacement Check Valve for Demco SBS Supplemental Braking Systems # SM99909.
view full answer... - Check Valve for SMI Supplemental Braking System on 2003 Jaguar X-TypeThe Replacement Check Valve # SM99909 that you referenced is designed for use with the SMI Stay-IN-Play DUO Braking System # SM99251 or the Air Force One # SM99243 and is needed on your Jaguar if you are installing either of these systems. The valve will indeed fit your vehicle. I have attached a couple diagrams taken from the installation instructions for these braking systems that you can take a look at as well.
view full answer...
- What Size Vacuum Line Does The Installer Use For Demco Stay-IN-Play On 2021 Jeep Wrangler JLU?When installing the Demco SBS Stay-IN-Play DUO Supplemental Braking System # SM99251 on a 2021 Jeep Wrangler like you seen in the installation video which I linked below, the installer used a section of the included 3/8" vacuum hose to install the Check Valve # SM99909.
view full answer... - Installation of SMI Replacement Check Valve on 2019 Ford RangerThe Replacement Check Valve for SMI Supplemental Braking Systems # SM99909 on your 2019 Ford Ranger will install in the either of those two hoses according to my tech contact at Demco (who owns SMI). He said you will install it only in whichever line you install the T-Fitting. The rubber hose will be easier for sure so that is my recommendation and the black side of the check valve needs to be on the engine side. I've attached a photo from the instruction manual of the SMI Stay-IN-Play...
view full answer...
- What are the Dimensions of SMI replacement Check Valve # SM99909I measured the Replacement Check Valve for SMI Supplemental Braking Systems # SM99909 for you. The overall diameter at the barbs for each end is 0.42 inches. The more narrow parts at the base have a diameter of 0.37 inches. The center, widest section is 0.76 inches in diameter. The overall length is 1.66 inches. This valve was designed to work with the Air Force One SM99202 or # SM99243 and Stay-IN-Play Duo # SM99251. So if you have one of these systems this is the correct replacement. If...
view full answer...
- Recommended Replacement Components for SMI Air Force One on 2019 Ford RangerYou can use the 1/4" Air Line Hose - SMI Air Force One or Stay-In-Play Duo Supplemental Braking System # DM16114 sold in 1 foot increments, so if you need 6 feet of new hose you can simply select quantity 6 on that product page and you will receive one 6 foot section of hose. The compression fittings like the Replacement Female Push-On Hose Connector for SMI Air Force One Supplemental Braking System # SM99726, the Replacement 1/4" Female Pushlock Fitting for SMI Supplemental Braking...
view full answer... - Is The Check Valve For Demco SBS Braking System Necessary.The Replacement Check Valve for Demco SBS Supplemental Braking Systems # SM99909 required for all towed vehicles that don't have a diesel engine and are not Hummers. A vacuum pump check valve for automobiles, also known as a vacuum check valve, is a part of your car that's responsible for making your vacuum pump system work. This valve seals and holds the vacuum flow up for energy-efficient and completely safe operation. You need it, for example, for your vehicle to brake properly.
view full answer... - Replacement Cap for Demco Air Force One Supplemental Braking System It sounds like you are looking for the Vinyl Cap for Demco SBS Air Force One Supplemental Braking System # SM99608.
view full answer... - Demco SBS Air Force One Replacement Parts for Poor Vacuum on 2018 Jeep JK RubiconThe Demco SBS Air Pressure Stop Light Switch Kit for Towed Vehicles - Air Force One # SM99629 will have that fitting you are referencing. You will also want to check any fittings like the Replacement 1/4" Female Pushlock Fitting for Demco SBS Supplemental Braking Systems - Qty 1 # SM99611 or check valves # SM99909. If the controller is the issue then you will need the Demco SBS Second Vehicle Kit for Air Force One Supplemental Braking System # SM99209. The controller is not available...
view full answer...
Do you have a question about this Accessories and Part?
Info for this part was:
Expert Research:
Michael H
Expert Research:
Jameson C
Installed by:
Jeff D
Installed by:
Michael B
Installed by:
Bradley B
Video Edited:
Jacob T
Video by:
Dustin K
Written by:
Wilson B
Updated by:
Kristina F
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Steven
8/17/2025
I have had the updated check valve installed on my 2017 Jeep Wrangler JK U with air Force one braking system installed and it has been working perfectly. Highly recommend using this valve as a replacement for the original valve.