C0631 on 2020-2021 Ford Explorer: AWD Malfunction Causes and Fixes

What's Unique About the 2020-2021 Ford EXPLORER

The sixth-generation Ford Explorer (introduced in 2020) and its platform mates, the Lincoln Aviator and Police Interceptor Utility, featured a new front axle disconnect system that proved problematic on vehicles built on or before August 30, 2021. The actuator component (FADA) was prone to failure, often due to a faulty internal O-ring seal that would harden, causing gear oil to leak and contaminate the unit's electronics. The actuator's failure to engage or disengage properly triggers the C0631 code. Ford acknowledged this widespread issue by releasing several Technical Service Bulletins (TSBs) that instruct technicians to replace the original actuator with a simplified, more robust intermediate shaft, effectively making the front axle permanently engaged and reprogramming the AWD module to work with the new hardware.

Diagnostic Flowchart

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

Symptoms You May Notice

• Illuminated powertrain malfunction (wrench) indicator on the dashboard.
• "AWD Malfunction Service Required" or similar service message displayed.
• Vehicle is stuck in two-wheel drive; loss of AWD capability.
• A deep whining or grinding noise from the front of the vehicle during acceleration.
• Visible gear oil leakage from the area where the front axle passes through the engine oil pan.

Most Likely Causes

1. Failed Front Axle Disconnect Actuator (FADA) 🔴 High Probability The original FADA design is susceptible to internal failures, particularly of its O-ring seal which can become hard like plastic, as documented in multiple Ford TSBs and numerous owner complaints. This allows gear oil to leak, leading to electronic and mechanical failure of the actuator.
   How to confirm: A technician will confirm by retrieving DTCs C0631 and often C00A6, then performing pinpoint tests with a scan tool. Visual inspection will likely reveal gear oil leaking from the actuator area near the oil pan.
   Typical fix: The official Ford repair is to replace the original FADA and intermediate shaft with a revised, non-disconnecting intermediate shaft assembly (Part No. N1MZ-3A329-A). This also requires a new left front halfshaft (Part No. N1MZ-3A427-F) to mate with the new shaft. The AWD module must then be reprogrammed using Ford's FDRS software to recognize the new hardware by selecting the option indicating the connector is no longer present. 🎬 Watch: How to perform the FDRS programming and module configuration.
   Est. part cost: $300-$500

Rare But Worth Checking

• Wiring Harness Damage: Damage or corrosion to the FADA's electrical connector or wiring can cause communication faults. The TSB repair procedure involves cutting off the original connector and sealing the wires, as it is no longer used with the revised hardware.
• AWD Control Module Failure: In very rare cases, the control module that commands the actuator may fail. This should only be considered after the actuator and wiring have been ruled out, as it is a much less common failure point for these symptoms.

Diagnosis Steps

1. Scan all vehicle modules for Diagnostic Trouble Codes (DTCs). Note C0631 and any accompanying codes like C00A6.
2. Reference Ford TSB 23-2174 for the official diagnostic 🎬 Watch: A deep dive into the TSB history and hardware changes. and repair procedure for vehicles built on or before August 30, 2021.
3. Visually inspect the Front Axle Disconnect Actuator (FADA) area on the driver's side of the engine oil pan for signs of gear oil leakage.
4. Using a Ford-specific scan tool (like FDRS), attempt to command the actuator on and off to test its electronic and mechanical function. A failure here confirms the fault.
5. If the actuator is unresponsive, leaking, or fails the pinpoint tests, proceed with the TSB-guided replacement of the actuator, intermediate shaft, and left front halfshaft.
6. After parts replacement, cut and seal the now-unused FADA electrical connector wires as per the TSB instructions.
7. Update the AWD module software to the latest level using FDRS, ensuring to configure the module for the non-disconnecting hardware by answering 'No' to the prompt asking if a connector is present, and clear all DTCs.

Parts You'll Likely Need

• Intermediate Shaft (Revised Design) (OEM #N1MZ-3A329-A) — This is the updated, non-disconnecting shaft that replaces the problematic FADA as per Ford's TSB 23-2174. It permanently engages the front axle.
  Trusted brands: Motorcraft
  OEM price range: $115-$250
  Aftermarket price range: $100-$200
• Halfshaft (Left Front) (OEM #N1MZ-3A427-F) — The TSB procedure requires replacement of the left front halfshaft because the inboard CV joint is a different design (female) to mate with the new intermediate shaft.
  Trusted brands: Motorcraft
  OEM price range: $200-$300
  Aftermarket price range: $120-$220
• Associated Nuts and Bolts (OEM #LB5Z-3B477-A, W715932-S439, W520517-S440, etc.) — The TSB calls for replacing several one-time-use nuts and bolts for the wheel hub, strut, engine mount, and stabilizer bar link during reassembly to ensure proper torque and safety.
  Trusted brands: Motorcraft
  OEM price range: $50-$100
  Aftermarket price range: $30-$60
• Front Axle Assembly Breather Hose (OEM #N1MZ-3B476-A) — TSB 23-2114 and later call for replacing the differential breather tube as part of the complete repair procedure.
  Trusted brands: Motorcraft
  OEM price range: $20-$40

Related Codes That Often Appear With This One

• C00A6 — This code specifically relates to the Front Axle Disconnect Actuator circuit performance. It is almost always present with C0631 as they both point to the same component failure, and both are explicitly mentioned in TSB 23-2174.

Technical Service Bulletins (TSBs) & Recalls

• TSB 23-2174: Supersedes previous bulletins, providing the definitive service procedure to replace the FADA and intermediate shaft with revised parts on Explorer and Aviator vehicles built on or before August 30, 2021. It includes an updated parts list and labor times.
• TSB 23-2114: An earlier, now superseded, version of the bulletin with the same core instructions but potentially different part numbers or labor times.
• TSB 25-2568: A placeholder TSB that notes DTCs C00A6 and/or C0631 may be due to the front axle disconnect actuator/intermediate shaft, directing technicians to the primary repair bulletin.

Platform-Specific Known Issues

• A known design flaw in the Front Axle Disconnect Actuator (FADA) on 2020-2021 models leads to high failure rates due to a hardened O-ring and subsequent oil leak.
• Ford's official repair, outlined in TSB 23-2174, is not just a replacement but a design change, eliminating the fuel-saving disconnect feature entirely in favor of reliability.
• Owner complaints frequently mention dealers quoting high repair costs, sometimes exceeding $2,500, for this specific TSB procedure, especially if the vehicle is out of the powertrain warranty.
• Some owners express frustration that the official "fix" involves removing a feature (the axle disconnect) that was part of the vehicle's original design.

Hidden / Shadow Codes Worth Checking

• C0631-7F: Indicates an intermittent or erratic mechanical failure of the Front Axle Disconnect Actuator. The '-7F' suffix points to the component not responding as expected, which is the typical failure mode. (see via This extended code is typically visible on dealer-level scan tools like Ford's IDS or FDRS, and may be reported in NHTSA ODI complaints.)

Scan Tool Commands That Help

• Ford FDRS (Ford Diagnostic & Repair System): AWD module software update — This function must be run after physically replacing the FADA with the revised intermediate shaft per TSB 23-2174. It re-programs the AWD module to operate without the disconnect feature.
• Ford FDRS (Ford Diagnostic & Repair System): Configuration prompt: 'Is there a connector plugged into the existing front axle disconnect actuator?' — During the 'AWD module software update' process, this prompt appears. The technician MUST select 'No' to inform the module that the actuator has been deleted. Selecting 'Yes' will result in a failed repair and persistent DTCs.
• Ford FDRS (Ford Diagnostic & Repair System): Active Torque Coupling configuration download — This may be required when replacing or reprogramming the AWD module to ensure the torque coupling is correctly calibrated.

Wiring & Ground Locations

• FADA Electrical Connector Pigtail — The wiring harness leading to the Front Axle Disconnect Actuator, located on the driver's side of the engine where the front axle passes through the oil pan.. As part of the official TSB 23-2174 repair, this connector is permanently cut off the harness. The four wires are then individually sealed with adhesive-lined heat shrink tubing and secured out of the way. This is a required step to prevent future wiring issues and is necessary for the software update to work correctly.

Real Owner Repair Stories

• YouTube channel 'Ford Boss Me - Auto / Politics / Family' (2020 Ford Explorer Police Interceptor Utility) — Leaking fluid from the FADA area, wrench light, and a stored DTC for the actuator.
  ❌ Tried (didn't work) Initially, the technician had only replaced the actuator without knowing the full TSB procedure, which led to a repeat failure. Early instructions with the parts were unclear or missing.
  ✅ What actually fixed it The final, correct repair involved replacing the faulty FADA with the revised intermediate shaft (deleting the disconnect feature), cutting off and sealing the electrical connector, and then using FDRS to perform the 'AWD module software update'. Critically, he showed selecting 'No' at the prompt asking if the connector was present, which successfully cleared the code and completed the repair.

OEM Part Supersession History

• Unknown (Original FADA) → N1MZ-3A329-A (Intermediate Shaft) — The original Front Axle Disconnect Actuator (FADA) had a high failure rate due to a faulty O-ring seal and internal electronics. The superseding part is not an actuator but a solid intermediate shaft that deletes the disconnect function entirely for improved reliability.
  Heads up: The new intermediate shaft (N1MZ-3A329-A) MUST be used with a new left front halfshaft (N1MZ-3A427-F) as the splines are different. Installing the new shaft without the matching halfshaft is not possible. The AWD module MUST be reprogrammed after installation.

Model Year Variations Within This Range

• 2020-2021: Per TSB 23-2174, vehicles built on or before August 30, 2021, are affected. However, the TSB also notes that some later-production vehicles within this range may have come from the factory with an intermediate shaft that is 'essentially a front axle disconnect actuator that does not have the connection being utilized.' The diagnostic and repair procedure varies slightly depending on whether the original electrical connector is present and in use.