P0735 on 2020-2023 Lincoln Aviator: Gear 5 Incorrect Ratio Causes & Fixes

What's Unique About the 2020-2023 Lincoln AVIATOR

The 2020-2023 Lincoln Aviator uses a 10-speed automatic transmission (10R60 or 10R80) that is known for a specific, widespread issue. A bushing inside the 'CDF' clutch drum assembly has a tendency to move out of place ('walk out'), uncovering a hydraulic fluid passage and causing a loss of pressure to multiple clutch packs. This single component failure is a well-documented cause for a host of gear ratio and shift performance codes, including P0735. Ford has issued multiple Technical Service Bulletins, with TSB 23-2123 being a key document that outlines the diagnostic and repair path for this exact problem across many Ford and Lincoln vehicles.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light or wrench light is illuminated
• Harsh, delayed, or failed shifts, particularly the 4-5 upshift.
• Transmission slipping (engine RPMs flare up without an increase in speed).
• Vehicle enters 'limp mode,' limiting available gears.
• Poor fuel economy.
• A jolt, bucking, or shuddering sensation during shifts.
• Feeling like driving over rumble strips during acceleration.
• Complete loss of power from a stop as the transmission struggles to engage a gear.

Most Likely Causes

1. Internal CDF Clutch Drum Failure 🔴 High Probability → Shop Transmission Clutch Pressure Plate The 10R60/10R80 transmission has a widely documented design flaw where a bushing in the CDF drum migrates, causing a seal to fail and a subsequent loss of hydraulic pressure. This is the primary issue addressed in multiple Ford TSBs. The updated replacement part includes a design revision to prevent the bushing from moving. 🎬 Watch: See how the CDF drum bushing fails and walks out.
   How to confirm: This is often a diagnosis of exclusion after fluid/filter and valve body issues are ruled out. Visual inspection during disassembly is the ultimate confirmation. TSBs may direct a technician to overhaul the main control valve body first before condemning the entire transmission.
   Typical fix: The transmission must be removed and disassembled. The CDF drum assembly is replaced with an updated part (Part No. JL3Z-7H351-B). Due to the labor involved, many shops recommend a full transmission rebuild or replacement with a remanufactured unit that includes all updates.
   Est. part cost: $300-$500 for the updated drum assembly; $4000-$7000+ for a remanufactured transmission.
2. Low or Contaminated Transmission Fluid 🟡 Medium Probability → Shop Transmission Assembly
   How to confirm: Check the transmission fluid level and condition according to the manufacturer's procedure. The fluid should be at the correct level, red in color, and not smell burnt or contain excessive metal particles. Note that these transmissions do not have a traditional dipstick and checking the level is a complex procedure.
   Typical fix: Perform a transmission fluid and filter change using the correct Motorcraft MERCON ULV fluid. This is often a first step, but it will not fix a mechanical fault like a failed CDF drum.
   Est. part cost: $150-$300 for fluid and filter.
3. Main Control Valve Body/Solenoid Failure ⚪ Low Probability → Shop Transmission Valve Body Debris from internal wear can cause valves or solenoids to stick. TSB 23-2123 lists overhauling the main control as a primary service step for these DTCs before condemning the entire transmission.
   How to confirm: A high-end scan tool can command individual shift solenoids to check for response. Pressure testing at specific ports can also help diagnose a valve body issue. The valve body is often overhauled or replaced as a diagnostic step before transmission removal.
   Typical fix: Replace or overhaul the main control (valve body) assembly. This is accessible after removing the transmission pan. 🎬 Watch: Step-by-step guide to replacing the 10R80 valve body. After replacement, the 13-digit solenoid body strategy must be programmed into the TCM using a tool like Ford IDS.
   Est. part cost: $800-$1500 for the assembly.

Rare But Worth Checking

• Faulty Transmission Speed Sensor (Input or Output): → Shop Transmission Assembly While possible, it's less common than the mechanical failures on this platform. The TCM uses these sensors to calculate the gear ratio, so a bad signal could trigger the code. This would often be accompanied by other speed sensor-specific DTCs.
• Wiring or Connector Issues: Damage to the transmission wiring harness can cause intermittent signals and incorrect readings, leading to this code. This is a possibility to rule out before major mechanical repairs.
• Powertrain Control Module (PCM/TCM) Failure: This is the least likely cause. TSBs often call for PCM/TCM software updates as a first step. The module should only be replaced after all other mechanical and electrical possibilities have been thoroughly ruled out.

Diagnosis Steps

1. Scan for all DTCs in the PCM and TCM. Note if P0735 is accompanied by other gear ratio or friction element codes, which strongly suggests a widespread internal issue.
2. Check for any applicable TSBs using the vehicle's VIN. Pay close attention to TSB 23-2123 and any newer superseding bulletins.
3. Check and verify the transmission fluid level and condition per the manufacturer's specification. Note that a dipstick is not present and this is a specialized procedure.
4. If recommended by a TSB, perform a PCM/TCM software update and the adaptive learning drive cycle.
5. Inspect the transmission wiring harness and connectors for any visible damage, corrosion, or loose connections.
6. Follow the diagnostic path in the relevant TSB, which often involves overhauling or replacing the main control valve body as a primary step.
7. If a valve body or transmission is replaced, the new 13-digit solenoid body strategy MUST be programmed into the TCM using a dealer-level scan tool.
8. If all prior steps fail to resolve the issue, the diagnosis points toward an internal mechanical failure, requiring the removal and teardown of the transmission for inspection and replacement of the CDF drum.

Parts You'll Likely Need

• CDF Clutch Drum Assembly (Updated) (OEM #JL3Z-7H351-B (supersedes HL3Z-7H351-A and JL3Z-7H351-A)) — This is the most common point of failure in the 10R80/10R60 transmission leading to code P0735. The internal bushing walks out, causing a pressure leak. The updated part has a revised design to prevent this.
  Trusted brands: Motorcraft, SunCoast Performance
  OEM price range: $300-$500
  Aftermarket price range: $300-$600
• Remanufactured Transmission — Due to the complexity of the repair and potential for widespread damage, many shops and owners opt to replace the entire unit with a remanufactured one that includes updated components and carries a warranty. A Ford remanufactured unit often comes with a 3-year, unlimited mileage warranty.
  Trusted brands: Motorcraft, Jasper
  OEM price range: $5000-$7000
  Aftermarket price range: $4000-$6000
• Transmission Main Control (Valve Body) (OEM #HL3Z-7G383-P (part number can vary, check with VIN)) — Can be a cause of shifting issues if valves are stuck. TSBs often list valve body overhaul or replacement as a diagnostic step before condemning the entire transmission.
  Trusted brands: Motorcraft
  OEM price range: $1000-$1500
  Aftermarket price range: $700-$1200
• Motorcraft MERCON ULV Automatic Transmission Fluid (OEM #XT-12-QULV) — This is the required fluid for any service or repair on the 10-speed transmission. A full rebuild requires approximately 13-14 quarts.
  Trusted brands: Motorcraft
  OEM price range: $10-$15 per quart

Related Codes That Often Appear With This One

• P0729, P0731, P0732, P0733, P0734, P0736 — These are incorrect gear ratio codes for other gears (Reverse, 1, 2, 3, 4, 6). They often appear with P0735 because the root cause, such as the CDF drum failure, affects hydraulic pressure to multiple clutch packs, causing slipping in several gears.
• P2700, P2701, P2702, P2703, P2704, P2705 — These codes relate to 'Transmission Friction Element Apply Time Range/Performance'. They indicate a clutch pack (e.g., clutch 'E' for P2704) is taking too long to engage, which is a direct symptom of the hydraulic pressure loss caused by a failing CDF drum.

Technical Service Bulletins (TSBs) & Recalls

• Harsh/Delayed Engagement And/Or Shift: This is the key TSB that supersedes several previous versions. It covers 2020-2023 Aviators and Explorers, among many other Ford/Lincoln models with 10R60/10R80 transmissions. It lists P0735 as a possible DTC and attributes the cause to PCM/TCM software, sticking valves in the main control body, and/or axial movement of the CDF clutch cylinder sleeve. The repair procedure can involve software updates, valve body overhaul, or CDF drum replacement.
• Harsh Shift And/Or Buck/Jerk/Hesitation Condition At Low Speeds: An earlier TSB specifically for the 2020 Aviator Hybrid, addressing harsh shifting and hesitation at low speeds with no DTCs. The prescribed fix was a PCM reprogram, indicating that software issues can cause similar symptoms and are often the first attempted fix.

Platform-Specific Known Issues

• The 10-speed automatic transmission in the 2020-2023 Aviator is susceptible to a failure of the CDF (Clutch 'C', 'D', and 'F') drum. A bushing inside the drum can migrate or 'walk' out of its intended position, uncovering a fluid passage and causing a major hydraulic pressure leak. This leak prevents clutches, including the 'E' clutch used for 5th gear, from engaging properly, leading to slipping and the P0735 code. Ford has acknowledged this design flaw by releasing an updated CDF drum assembly (part number JL3Z-7H351-B) that physically prevents the bushing from moving. This issue is not unique to the Aviator and affects a wide range of Ford and Lincoln products using the 10R80/10R60 transmission, as documented in TSB 22-2428.

Mechanic-Grade Diagnostic Values

• Shift Solenoid Resistance — expected: 5.0 - 5.4 Ohms at 20°C (68°F). Failure: A resistance reading outside of this range indicates a faulty solenoid.
• Torque Converter Clutch (TCC) Solenoid Current — expected: Proportional operation. Low current (50 mA) results in low pressure; high current (850 mA) results in high pressure.. Failure: Pressure readings that do not correspond with the commanded current on a scan tool.
• Line Pressure Control (LPC) Solenoid Current — expected: Inversely proportional operation. Low current (50 mA) results in high pressure; high current (850 mA) results in low pressure.. Failure: Pressure readings that do not correspond with the commanded current on a scan tool.

Hidden / Shadow Codes Worth Checking

• Mode $06 Misfire Counts: In some cases, intermittent engine misfires that are not severe enough to set a P030x DTC can confuse the TCM, leading to gear ratio codes like P0735. These can only be seen by monitoring Mode $06 emission data for misfire counts on individual cylinders. (see via A high-end scan tool capable of displaying Mode $06 data.)

Scan Tool Commands That Help

• Ford IDS, FORScan: Clear Transmission Adaptive Tables / Reset KAM — This function is used to erase the transmission's learned shift patterns. It is required after most transmission repairs, including fluid changes, valve body work, or transmission replacement, and must be followed by the Adaptive Learning Drive Cycle.
• Ford IDS, FORScan: Adaptive Learning Drive Cycle — A specific, multi-step driving procedure that must be performed after clearing the adaptive tables to allow the TCM to relearn clutch fill times and shift points. Failure to perform this can result in continued erratic shifting.
• Ford IDS: PCM - Transmission Strategy Download (Solenoid Body Strategy Programming) — This is a mandatory procedure after replacing the main control (valve body) or the entire transmission. The 13-digit strategy number from the new part must be programmed into the TCM for it to control the new solenoids correctly.
• FORScan: Halt Transmission Adaptive Learning — An advanced function that can be used to stop the transmission from further adapting its shift strategy. This is sometimes used by advanced users to lock in a good shift feel after the learning process is complete, but is not part of a standard Ford procedure.

Wiring & Ground Locations

• Fuse F22 (Underhood) — In the underhood fuse box, position 22 is listed for the Powertrain Control Module power.. Loss of power to the PCM would cause a host of issues, including loss of transmission control.
• Fuse F70 (Passenger Compartment) — In the passenger compartment fuse box, position 70 is listed for the Transmission Control Module.. A blown fuse here would cut power to the TCM, leading to a no-shift condition and multiple DTCs.
• Shift Solenoid D Connector Wire — On the transmission main control connector. The wire for ground control is Brown with a White stripe (BN-WH).. Damage to this specific wire could prevent Solenoid D from being controlled correctly, potentially contributing to shift issues, although P0735 is more directly related to the 'E' clutch.

Real Owner Repair Stories

• Gears Magazine (2019 Ford F-150, 3.5L Engine, 10R80 Transmission) — P0735 (Gear Ratio Error in 5th) and P2704 (Friction Element 'E' Apply Time) codes, with confirmed slip in 5th gear.
  ❌ Tried (didn't work) Complete transmission teardown and inspection (found no visible faults)., Reassembly with a new, updated CDF drum., Reassembly with a new dealer-sourced valve body.
  ✅ What actually fixed it The technician discovered intermittent, non-DTC-setting misfires on cylinders #1 and #5 by analyzing Mode $06 data. Swapping ignition coils confirmed faulty coils were the root cause; the engine misfires were confusing the transmission controller and causing the slip symptom.
• Reddit user on r/f150 (Ford F-150 with 10R80) — Clunky 4th to 3rd downshift.
  ❌ Tried (didn't work) One user reported a dealer first replaced the valve body, which did not solve the issue.
  ✅ What actually fixed it The dealer diagnosed a CDF drum failure. The CDF drum was replaced with the updated part, which resolved the harsh shifting.
• Ford-trucks.com forum user (2020 Ford F-150 XLT) — After having the transmission replaced with a new unit (with updated CDF drum) at an independent shop, the truck had jerky shifts, clunking, and stuttering.
  ❌ Tried (didn't work) Replacing the entire transmission with a new unit.
  ✅ What actually fixed it The issue was unresolved in the post, but a reply from a Master ASE Tech pointed out two likely missteps by the independent shop: 1) The original torque converter was likely reused, potentially contaminating the new transmission with old debris. 2) The shop may not have performed the necessary solenoid strategy programming and adaptive learning reset after installation. This serves as a cautionary tale for the repair process.

"I Checked Everything" — The Actual Cause

• A well-documented professional case involved a 10R80 with P0735 where the transmission was completely torn down and rebuilt with an updated CDF drum and a new valve body, yet the 5th gear slip persisted. The ultimate cause was found to be intermittent engine misfires, not severe enough to set an engine code, but visible in Mode $06 data. The engine's slight rotational speed variations were enough to trick the TCM into thinking the transmission was slipping.

When the Usual Fixes Don't Work

• While the CDF drum failure is the most common cause for P0735 on the 10R80 transmission, it is not the only cause. In one documented case, a shop replaced the CDF drum and valve body, but the problem persisted. The actual root cause was found to be minor engine misfires that were not setting a fault code. This demonstrates that if the common, major mechanical fixes do not work, the diagnostic focus should shift to external inputs that could be confusing the transmission control module.

OEM Part Supersession History

• HL3Z-7H351-A, JL3Z-7H351-A → JL3Z-7H351-B — The original CDF drum assembly contained a bushing that could migrate or 'walk out' of its bore, uncovering a fluid passage and causing a major hydraulic pressure leak. The updated JL3Z-7H351-B part has a revised design with a lip on the bushing to prevent it from moving.

Model Year Variations Within This Range

• 2020-2022 (Primarily): Vehicles manufactured in the earlier part of this range are more likely to have the original, failure-prone CDF drum design from the factory. While the issue can still occur on 2023 models, Ford began incorporating updated parts at the factory level around this time, potentially reducing the failure rate on later builds. However, TSBs still list 2023 models as potentially affected.