An Expedition is a heavy three-row SUV that often has a trailer behind it, and it runs the same 10R80 10-speed and 3.5L EcoBoost as the F-150. When an owner says it "slips," that can mean an RPM flare on an upshift, a 2-3 or 4-5 that slides before it bites, a soft or late pickup into Drive, or the tach climbing on a grade with no shift at all. Each one points somewhere different, and the most expensive answer means pulling a transmission Ford rates at 11 to 13 hours of labor in an Expedition. This guide sorts the complaint by gear first, then walks the repair path Ford publishes for the 2018-2024 Expedition and Navigator.
The facts below come from Ford's own service bulletins as filed with NHTSA, Ford's 10R80 workshop manual section 307-01, an ATRA GEARS Magazine case study and Sonnax tech material. Links are in the Sources section at the bottom. For the non-slip Expedition problems, including the 2026 park pawl recall, see our 10R80 Expedition common problems guide.
Which Ford bulletin fits your Expedition
The build date decides the starting point. Look at the door tag before anything else.
- 2018-2021 Expedition and Navigator: TSB 23-2152 (May 2023) covers harsh engagement and harsh or delayed shifts with slip-ratio codes stored. Ford's stated causes are the keep alive memory in the PCM and the main control valve body. The fix is a software update and adaptive relearn first, then a main control valve body overhaul.
- 2022 Expedition and Navigator built on or before 15-Aug-2022: TSB 24-2304 (September 2024) adds a hard-parts cause: axial movement of the CDF clutch cylinder (7H351) sleeve, which leaks C, D and F clutch apply oil. It includes a line pressure test that proves the leak before the transmission comes out.
- 2022-2024 built 16-Aug-2022 through 23-Sep-2024: the known issue on these is TSB 26-2241, harsh 3-4, 4-5 and 4-3 shifts from F clutch plates brinelling into the container. Owners sometimes describe that bump as a slip. We cover it in the Expedition common problems post.
The same list of codes shows up in both 23-2152 and 24-2304: P0751 through P0772 (shift solenoid performance), P2700 through P2708 (friction element apply time), and the gear ratio codes P0729, P0731 through P0736, P076F, P07D9, P07F6 and P07F7. The ratio codes are the ones that matter for a slip complaint, because each one names the gear where the PCM saw input and output speeds disagree with the commanded ratio.
Match the slipping gear to the clutch
The 10R80 has four planetary sets, six friction clutches (A through F) and one one-way clutch. Each clutch has its own linear force solenoid, SSA through SSF, and Ford's description section notes the solenoids are directly proportional: zero current is zero pressure, maximum current is maximum pressure. That means a slip is either low apply pressure to a clutch, a leak in its circuit, or a worn clutch pack. The application chart from Ford's 307-01 specifications tells you which clutches are on in each gear.
| Gear | Applied clutches | Ratio code |
|---|---|---|
| 1st | A, E (D applied only to cut drag), OWC holding | P0731 |
| 2nd | A, C, D | P0732 |
| 3rd | A, C, D, E | P0733 |
| 4th | A, C, D, F | P0734 |
| 5th | A, C, E, F | P0735 |
| 6th | A, D, E, F | P0729 |
| 7th | C, D, E, F | P076F |
| 8th | B, D, E, F | P07D9 |
| 9th | B, C, E, F | P07F6 |
| 10th | B, C, D, F | P07F7 |
| Reverse | A, B, D, F | P0736 |
Read it like a builder. A slip only in 8th through 10th points at B, the only clutch common to those three and absent everywhere else in forward. A slip in 1st and 3rd but not 2nd leans toward E. Slips scattered across 2nd, 4th, 7th and 10th with reverse also soft point at D or F, and that is the pattern the CDF cylinder leak produces, because one leaking cylinder feeds three clutches that between them are on in every gear from 2nd up. If every gear from 1st to 6th flares and 7th is fine, look hard at A.
Log it, do not guess
Ford's 10R80 uses a turbine shaft speed sensor, two intermediate speed sensors (ISSA and ISSB) and an output shaft speed sensor. Record TSS, OSS, commanded gear, engine RPM, TFT and line pressure desired during the complaint. Divide turbine speed by output speed. If that number wanders off the commanded ratio, a gear clutch is slipping. If the ratio holds steady but engine RPM runs above turbine speed with the converter commanded on, the slip is in the torque converter clutch, not the geartrain, and that is a different job. A towing Expedition at 65 mph in 10th on a long grade is the best place to catch either one, so make the test drive match the complaint.
Check the engine before you blame the transmission
This is the one that saves the most money on an EcoBoost. ATRA's GEARS Magazine documented a 2019 F-150 with the 3.5L and 10R80 that slipped in 5th only, and only hot, with P0735 (5th gear ratio) and P2704 (E element apply time). Two builders replaced a dealer valve body, an updated CDF drum, and the E clutch drum and piston. The slip and codes stayed. Data showed the PCM commanding solenoid E erratically right after the slip, and Mode $06 showed misfire counts on cylinders 1 and 5 that were too low and steady to set a P030x code. New spark plugs fixed the transmission.
The Expedition runs the same engine and the same PCM strategy. Before a teardown, pull Mode $06 misfire counts, look at the plugs on a high-mileage or tuned truck, and confirm there are no engine codes the owner has been ignoring. A misfire changes the torque the PCM thinks it is managing, and on a 10-speed with clutch-to-clutch shifts that can show up as a shift fault.
The cheap causes Ford lists first
TSB 23-2152 puts keep alive memory at the top for the 2018-2021 Expedition. The adaptive tables can learn bad values after a battery issue, a module update or a period of hard use, and then shifts land late or soft. Ford's sequence is: load test and charge the battery, update the PCM to the latest calibration, clear adaptives and perform the adaptive learning drive cycle from 307-01. Ford warns that the relearn can make shifts firmer than normal for several days, so set that expectation with the owner.
Fluid level and fluid type
Ford's 10R80 specification calls for Motorcraft MERCON ULV (XT-12-QULV, spec WSS-M2C949-A) and states that transmission fluids are not interchangeable and other fluids will cause internal damage. Check the level on a level surface at normal operating temperature, which Ford gives as 206-215 F (96-101 C). Ford lists 12.5 qt for a completely dry 10R80 and converter, and a pan drain takes far less, so fill to the hot mark, not by quart count. Low fluid lets the pump draw air on hard acceleration, braking and long curves, which drops line pressure and feels exactly like a clutch slip. An overfilled unit vents and runs hot, and a hot 10R80 behind a trailer is where marginal seals start to leak.
When it is the valve body
If the slip survives software, relearn and a correct hot level, 23-2152's next step on a 2018-2021 Expedition is a main control valve body overhaul. The 10R80 solenoids do not pass fluid; each one pushes a pin against a control valve in the valve body, so a sticking or worn control valve gives the same symptom as a weak solenoid. Ford's bulletin calls out different separator plates by shifter on the Expedition: JL1Z-7Z490-C for the rotary dial and JL3Z-7Z490-E for column shift. Order the wrong one and you build a new problem into the unit.
When it is the CDF cylinder: prove it with pressure
On a 2022 Expedition built on or before 15-Aug-2022, TSB 24-2304 gives Ford's test. It takes 1.4 hours on an Expedition, which is cheap next to the 11.4 hours (4x4) or 12.7 hours (4x2) Ford allows to pull the unit and replace the cylinder. The outline:
- Install a pressure transducer in the line pressure port. The port is M10x1.0, not pipe thread, so use an M10x1.0 male to 1/8 FNPT adapter and seal the NPT side with PTFE.
- Monitor LINEDSD, the transducer pressure, RPM, RPM_DSD, SSA_AMP through SSF_AMP, TR_Corrected and TFT. Park, parking brake on, TFT at 122 F (50 C) or above.
- Command all six shift solenoids to 0 mA, engine speed to 500-600 RPM, and line pressure desired to 1900-2000 kPa (275-290 psi). Actual line pressure will read lower than commanded; that is normal.
- Record while commanding SSA to 1.0 A for two seconds, then repeat for SSC.
- Enter the pressure peaks and valleys before and during each apply into Ford's CDF calculator. If the A clutch leakage rate fails, the A clutch circuit is the problem and the bulletin does not apply. If A passes but the C clutch versus A clutch comparison fails, the CDF cylinder is leaking and the transmission comes out.
The 2018-2021 Expedition is not on 24-2304's model list. It uses the same CDF design, so a leak proven with the same pressure method is still a leak, but the warranty and bulletin path for those years runs through 23-2152.
Do not condemn it with an air check
Ford's SSM 54674 for 2021-2026 10R80s introduced a Transmission Clutch Circuit Leak Test in FDRS and says the old air check method produced a high rate of false positives. Ford states the air check is not to be used to diagnose internal hydraulic leaks or to justify replacing a transmission. On the bench it is a different story. Sonnax recommends air checking each drum with its input and mating part, then the full assembly through the pump before it goes in the case, and names sealing ring and hub bushing wear as among the biggest causes of lost apply pressure in these units.
Doing the teardown right
When the cylinder comes out, 24-2304 has you replace the converter seal, front support bolts and seals, input shaft and sun gear shaft seals, and the C, D and F balance dam and piston seals. The bulletin lists three 7H351 cylinders by application; the F-150, Expedition and Navigator part is ML3Z-7H351-B. Inspect the C, D and F packs while you are in there; a cylinder that leaked long enough on a towing Expedition will have cooked frictions. Sonnax's CDF Drum Saver Kit (129910-01K) covers the 10R80 for worn drums. After installation, run the adaptive drive cycle before the vehicle goes back.
How I work a slipping Expedition 10R80
- Door tag. Model year, build date, rotary dial or column shift.
- Log the slip. TSS, OSS, commanded gear, TFT. Name the gear and the clutches it shares.
- Engine first. Mode $06 misfire counts, plugs, engine codes.
- Battery, software, relearn. Then a hot level check with MERCON ULV only.
- Valve body on a 2018-2021 that still fails, with the right separator plate for the shifter.
- Prove a CDF leak with the line pressure test or the FDRS leak test before the unit comes out.
10R80 deluxe rebuild kit for the CDF teardown
If the pressure test says the CDF circuit is leaking, the clutch and planetary assembly comes apart and the seals Ford lists get replaced. This deluxe kit covers 2017-up 10R80s, Expedition and Navigator included, so the seals are on the bench before the case is open.
Shop the part for this fix →Need valve body parts too? The 10-speed parts collection has the Sonnax valve body kits and parts the Ford and GM 10-speeds share.
Need parts for this job?
The Sonnax Zip Kit for a valve body overhaul, master rebuild kits, friction modules and MERCON ULV-spec fluid for the Expedition 10R80 are on our 10R80 parts page, with checkout on site.
FAQ
Why is my Ford Expedition transmission slipping?
On a 2018-2024 Expedition 10R80, Ford's bulletins point to PCM keep alive memory, sticking valves in the main control valve body, and on 2022 units built by 15-Aug-2022 a moving CDF clutch cylinder sleeve that leaks C, D and F apply oil. Low or wrong fluid and an engine misfire can feel the same. Check the fluid hot and relearn the adaptives before blaming hard parts.
Is there a TSB for a slipping Expedition 10R80?
Yes. TSB 23-2152 covers 2018-2021 Expedition and Navigator with harsh or delayed shifts and gear ratio codes, fixed with software, an adaptive relearn and a valve body overhaul if needed. TSB 24-2304 covers 2022 Expedition and Navigator built on or before 15-Aug-2022 and adds a line pressure test and CDF cylinder replacement, part ML3Z-7H351-B.
Can an engine misfire make a 10R80 slip?
It can. ATRA's GEARS Magazine documented a 3.5L EcoBoost 10R80 that slipped in 5th with P0735 and P2704 after two valve bodies and clutch parts failed to fix it. Mode $06 showed low misfire counts on two cylinders, and new spark plugs cured the transmission complaint.
What fluid does the Expedition 10R80 take and how do I check it?
Motorcraft MERCON ULV, XT-12-QULV, spec WSS-M2C949-A. Ford says other fluids will cause internal damage. Check it on a level surface at 206-215 F and fill to the hot mark, because a drain takes far less than the 12.5 qt dry capacity.
Does an air check prove a CDF leak on an Expedition?
Not in the vehicle. Ford's SSM 54674 says the in-car air check gives a high rate of false positives on 2021-2026 10R80s and must not be used to justify replacing a transmission. Use the FDRS clutch circuit leak test or the TSB 24-2304 line pressure test. Bench air checks of a drum with its mating shaft are still valid.
Related guides
- 10R80 Expedition Common Problems and Fixes
- 10R80 Slipping Under Load
- 10R80 Harsh and Delayed Shifts
- 10R80 Ranger Slipping: Causes and Fix
- 10R80 Valve Body Problems and Testing
Sources
- Ford Motor Company — Technical Service Bulletin 24-2304, "Various Vehicles Equipped With A 10R80 Automatic Transmission — Harsh/Delayed Engagement And/Or Harsh/Delayed Shift — Built On Or Before 15-Aug-2022" (24 Sep 2024). 2022 Expedition/Navigator applicability, DTC list, CDF cylinder 7H351 sleeve movement, M10x1.0 port, PIDs and line pressure test values, CDF calculator steps, Expedition labor times, seal list, CDF cylinder ML3Z-7H351-B for F-150/Expedition/Navigator. static.nhtsa.gov (PDF)
- Ford Motor Company — Technical Service Bulletin 23-2152, "10R80 — Harsh Engagement And/Or Harsh/Delayed Shift" (22 May 2023). 2018-2021 Expedition/Navigator applicability, keep alive memory and main control valve body causes, software and relearn sequence, valve body overhaul, shifter-specific separator plates. static.nhtsa.gov (PDF)
- Ford Motor Company — SSM 54674, "Various 2021-2026 Vehicles — 10R80 — New Transmission Clutch Circuit Leak Test In FDRS." New FDRS leak test, air check false positives, air check not to justify replacement. static.nhtsa.gov (PDF)
- Ford Motor Company — Workshop Manual Section 307-01, 10R80 "Specifications" and "Description and Operation" (2019 model year, rev. 12/11/2018). MERCON ULV WSS-M2C949-A, 12.5 qt dry fill, 206-215 F check temperature, clutch application chart, proportional A-F shift solenoids, speed sensors. Specifications (PDF) · Description and Operation (PDF)
- ATRA GEARS Magazine — "A 10R80 with P0735 and P2704 Issues." 2019 F-150 3.5L 5th-gear slip, solenoid E commanded in 1st, 3rd and 5th-9th, Mode $06 misfire counts on cylinders 1 and 5, spark plugs as the fix. gearsmagazine.com
- Sonnax — "Troubleshooting Pressure Loss in 10-Speed Clutch Packs." Sealing ring and hub bushing wear as a top cause of apply pressure loss, bench air check method, CDF Drum Saver Kit 129910-01K, ULV-only fluid. sonnax.com