Of the ten FCA service documents on this page about the Ram 1500 four-corner air suspension, sales code SER, eight end in a software reflash of the air suspension control module (ASCM), one in a fuse, and one in a rear air spring. Bulletins are not a tally of repairs, and a compressor replaced by the standard procedure never gets one; what these do show is that on the trucks they name, a wrong height, a “Service Air Suspension” message or a cold-morning no-rise was fixed in the module, in a 0.2 hour operation, so the bulletin, the build date and the stored codes are read before a part is approved. DS and DT are FCA’s generation codes from the bulletin headings, the 2013 to 2016 trucks here being DS and the 2020 and later ones DT.
The heights themselves come from the 2021 owner’s manual: Normal Ride Height, Off-Road 1 about 26 mm up, Off-Road 2 about 51 mm up, Aero about 15 mm down, Entry/Exit about 51 mm down, each tied to a speed that enters and leaves it. A truck that “will not go to Off-Road 2” at 30 mph is doing what that manual says. Below: what each message and stuck height has meant in the bulletins, the fuse FCA checks before anything else, and the one leak that got a parts bulletin.
Quick answer
Note the height the truck is stuck at and the speed you were doing, read the stored codes, and check the compressor fuse before any part is named.
| What you see | Where to look | What to do first |
|---|---|---|
| “Service Air Suspension” after a battery disconnect, code U0422 | ASCM software (2020 DT, bulletin 08-078-20) | Reflash, not a part |
| Stuck low in Entry/Exit after loading the bed and driving on the freeway, “Service Air Suspension” | ASCM software (2022 to 2024 DT: 08-150-24, 08-152-24, 08-151-24) | Reflash; on the 2022 and 2023 trucks the check engine light and a ride height sensor “stuck” code go with it |
| Will not change height in real cold, check engine light | Compressor fuse, then ASCM software (2015 to 2016 DS, 08-051-16) | Fuse first, in the case’s cold-weather branch: an open fuse is replaced on its own, then dryer purge and nitrogen fill |
| Leans left or right, or sits low at the rear, 2025 DT built Sept 25 to Nov 6, 2024 | Rear air springs (17-002-25) | Read the label on both rear springs: 24 276 to 24 296 is the replaced range |
| “Battery Voltage Low – Start Engine to Change Ride Height” on locking, battery goes flat | ASCM software (2013 to 2014 DS, 08-045-14) | Reflash; the module was staying awake |
Each row has more than one cause behind it; the build date and the stored codes decide which bulletin applies.
The heights, and the speeds that move them
The 2021 Ram 1500 manual gives the four-corner system five positions and a speed rule for each. Off-Road 1 raises the truck about 26 mm, is entered with one push up below 35 mph, and drops back to normal after more than 20 seconds at 40 to 50 mph or above 50 mph. Off-Road 2 adds about 51 mm, is entered below 20 mph, and drops to Off-Road 1 above 25 mph. With automatic Aero enabled, Aero lowers the truck about 15 mm by itself after more than 20 seconds at 62 to 66 mph or above 66 mph, and comes back up after more than 20 seconds at 30 to 35 mph or below 30 mph. Entry/Exit lowers about 51 mm: requested below 33 mph, it starts lowering below 15 mph, is cancelled by more than 60 seconds at 15 to 25 mph or by passing 25 mph, and returns to normal with one push up or by driving over 15 mph. The Off-Road Group trucks get one Off-Road position of about 26 mm and an Entry/Exit of about 73 mm.
Three more rules from the same pages get reported as faults. Lowering stops with any door open until it is closed. The system “operates briefly” after the engine is turned off to correct the parked position, which the manual calls normal. And the Protection Strategy disables load leveling when the suspension is overloaded or the battery charge is low, lights the payload protection lamp, and resumes by itself when conditions are met.
What FCA’s bulletins fixed, year by year
The DS trucks got two early flashes. Bulletin 08-022-13, for 2013 trucks built before February 5, 2013, answers a rough ride above 62 mph by moving Aero from 27 mm down to 15 mm down, where the 2021 manual still has it. Bulletin 08-045-14 Rev A, for 2013 to 2014 trucks built on or before May 10, 2014, cures a false “Battery Voltage Low – Start Engine to Change Ride Height” message on locking and a battery drain when the key fob was used to stop the truck lowering: the module did not go to sleep and kept the CAN-C bus awake. Its repair note is worth knowing on those trucks: a module that stops responding during the flash gets fuse F50 pulled in the underhood power distribution center and the flash run again, not a new module.
Bulletin 08-051-16 covers 2015 to 2016 DS trucks built December 4, 2014 to February 22, 2016 that would not change height “in real cold conditions”, with a check engine light and up to seven codes: C15A1-00, C1562-98, C1562-92, C159F-92, C15A0-92, C155E-92 and C15AA-00, naming the pump, both reverse valves, the vent and an air leak during vent. The remedy is a reflash, not a pump, not a valve.
FCA’s STAR case S1723000007 Rev F, “Air Suspension Inoperative And Or Compressor Freeze Up Or Sticking In Cold Weather”, names no model years, only that Rebel trucks use the Off Road position, and it starts with the fuse. Fuse open: replace the compressor fuse only, “not the compressor unit”, deflate the system to atmosphere to purge the dryer, fill the reservoir with nitrogen, run three partial deflations with the tool to pull humidity out, fill the system with nitrogen, then leak-test. Fuse not blown: follow the diagnostics for whatever code is stored, and with no code stored, run the suspension through each position and watch it. The case also has the intake air hose checked for pointing downward, so water does not collect in it, and notes that an updated compressor exists for trucks where no moisture, leak or mis-routed intake is found.
The next five DT bulletins are software. 08-078-20, 2020 trucks built on or before July 8, 2020: “Service Air Suspension” and U0422-00 after a battery disconnect. 08-150-24 for 2022 trucks and 08-152-24 for 2023 trucks, both of June 28, 2024 and both replacing 08-127-23, which had covered the two years together with a build-date limit the revisions dropped: a check engine light with at least one of the ride height sensor stuck codes C151E-2A, C1522-2A, C1526-2A and C152A-2A, and with it “Service Air Suspension” or a truck stuck low in Entry/Exit after the bed was lowered for loading and the truck driven on the freeway. 08-151-24, 2024 trucks: the same stuck-low complaint. 08-191-24, 2025 trucks built on or before July 29, 2024: a check engine light with button stuck code C15A7-2A or C15A8-2A, and with it “Warning Service Air Suspension” or a truck stuck in Entry/Exit. Each reprograms the ASCM with a battery charger connected, and most of them specify 13.2 to 13.5 V during the flash.
The one parts bulletin among these is 17-002-25 Rev A, for 2025 DT trucks built September 25 to November 6, 2024 with standard or raised ride height: an air leak from the rear air springs makes the truck lean to the left or right or sit low at the rear. The technician reads the label on both rear springs; a number from 24 276 to 24 296 means that spring, or both, is replaced. The same action went out as Rapid Service Update 25-011, so a dealer can check a VIN against it. The bulletin’s first step is to raise and support the truck; nobody reads that label under a truck held up by its own air springs.
Compressor fault, or something else?
| Symptom | Competing causes | Clues that shift suspicion |
|---|---|---|
| Truck will not rise on a cold morning | Open compressor fuse; cold-weather software (2015 to 2016 DS); a leak; a compressor | The STAR case starts at the fuse; an open fuse is replaced on its own and the dryer purged. Seven cold-weather codes on a 2015 to 2016 DS point at 08-051-16 before any part |
| Stuck at Entry/Exit, will not come up | ASCM software (2022 to 2025 DT); payload protection; low battery charge | 08-150-24 and 08-152-24 list the sensor-stuck codes for 2022 and 2023 DT trucks and 08-191-24 the button-stuck codes for 2025 DT trucks built on or before July 29, 2024; the payload protection lamp means the payload may be exceeded or leveling cannot be reached at that height, and the manual has leveling resume on its own once conditions are met |
| Leans to one side or low at the rear | Rear air spring (2025 DT build window); a leak elsewhere; a line | A 2025 truck built in the six-week window gets the label check first. Outside it, the single-corner page covers how the overnight behaviour steers the search between a spring, a line and a valve |
| Drops to normal when you wanted Off-Road 2 | Speed rule, by the 2021 manual; a real fault | Above 25 mph the truck leaves Off-Road 2 by design and above 50 mph it leaves Off-Road 1; a drop with a warning or a rough ride is something else |
What to check first
- The compressor fuse, from the fuse chart. FCA’s cold-weather case opens with it, replaces an open fuse on its own, and goes on to the dryer purge and nitrogen fill; a fuse that is good sends the diagnosis to the stored codes. A higher-rated fuse is not a repair.
- The build date against the bulletin windows. Each bulletin names its trucks by generation, and most by build date too, from “before February 5, 2013” to the six-week rear-spring window of September 25 to November 6, 2024, while the 2024 revisions for the 2022 to 2024 trucks dropped the build-date limit; the certification label on the door jamb gives the month and year, the exact day comes from the VIN build record, and the windows are in the sources below.
- The codes, read as a set, and the per-corner hold if they name no circuit. Sensor-stuck, button-stuck, U0422 and the seven cold-weather codes each map to a flash above. When no code names a corner and the truck still loses height, FCA’s own leak test raises the truck to Off-Road 2, records pressure and air mass per corner, puts the module in plant mode, which stops leveling and sets C2212, waits two hours and compares; the leak test page has the sequence and its limits. Plant mode ends by completing a module routine on the tool, not by clearing the code.
Can you drive on it?
Speed-dependent height changes that match the manual are not a fault. A truck stuck low or showing a warning reached the dealer in every bulletin here, and the manual’s cautions for the low and high settings are about clearance: at Entry/Exit “you may not have the clearance required for certain areas and vehicle damage may occur”. The manual’s warning about the system itself is about service: it “uses a high pressure volume of air”, and work on it goes to a dealer.
Stop driving if:
- the truck keeps a lean to one side or sits low at the rear after the engine has run, the rear-spring case;
- the truck is stuck at Entry/Exit height and the road ahead has less clearance than that height allows;
- a corner is down far enough that the tire is near the arch, or the handling has changed; that truck is moved on a flatbed in Transport Mode, the mode the manual names for tying down from the body; if the engine will not run and Transport Mode cannot be set, the manual has the tie-downs fastened to the axles, not the body.
FAQ
How do I reset the Ram 1500 air suspension?
There is no reset button; the bulletins clear codes only after a reflash or a repair. What looks like a reset is in the manual: Tire/Jack, Transport and Wheel Alignment modes switch off by driving the truck, and leveling disabled by payload or low battery charge resumes by itself.
What does “Service Air Suspension” mean on a Ram 1500?
The module stored a fault. In the bulletins here it came with U0422-00 after a battery disconnect, with sensor stuck codes after a height change, and with button stuck codes on 2025 trucks; each time the repair was software. The code with the message says which.
Why does my Ram lower itself at highway speed?
Aero mode, in the 2021 manual, with automatic Aero enabled: after more than 20 seconds at 62 to 66 mph, or above 66 mph, the truck drops about 15 mm. Early-build 2013 trucks dropped 27 mm and could ride rough at a steady speed above 62 mph, until bulletin 08-022-13 changed the figure. Automatic Aero can be switched off in the cluster or Uconnect settings.
Why won’t my Ram air suspension work in the cold?
Two documented causes: software on 2015 to 2016 DS trucks in the bulletin’s build window, and moisture freezing in the compressor and opening the fuse on any truck, where the open-fuse branch replaces the fuse, purges the dryer and fills with nitrogen and leaves the compressor in place.
How much does Ram air suspension repair cost?
None of the documents publishes a price. They publish labor allowances, which are not quotes: each of the eight ASCM reflashes is 0.2 hours, the rear spring inspection 0.3, one spring 0.7, both 1.0; diagnosis and parts are separate. Do not approve a compressor on the warning alone; the fuse and the stored faults come first. Delete kits are a different decision and not covered here.
