U0109 on 2018-2024 Ford Expedition: Lost Communication With Fuel Pump Control Module Fixes

What's Unique About the 2018-2024 Ford EXPEDITION

For this generation of Ford Expedition and its platform mates (like the F-150 and Lincoln Navigator), the U0109 code is so commonly associated with a specific wiring problem that Ford has issued multiple Technical Service Bulletins (TSBs). The issue is often not the control module itself, but an intermittent or partial disconnect of the electrical harness connector (C433 or C4033) leading to it. The module's location on the frame rail exposes it to vibration and moisture, making this connection a known weak point. This makes diagnosis more straightforward than on other vehicles where the module itself is the more frequent point of failure.

Diagnostic Flowchart

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

Symptoms You May Notice

• Engine cranks but will not start.
• Sudden engine stalling while driving.
• Hesitation or loss of power during acceleration.
• Check engine light is on.
• Wrench light may be illuminated on the dashboard.
• Vehicle enters a reduced power or 'limp' mode.

Most Likely Causes

1. Loose or Disconnected FPCM Harness Connector 🔴 High Probability This is a well-documented issue cited in multiple Ford TSBs (SSM 52483, SSM 51306, SSM 49618, SSM 50661) for this platform. The connector's locking tab can break, or it can simply vibrate loose, leading to intermittent communication loss. Its location on the frame rail makes it susceptible to this.
   How to confirm: Locate the Fuel Pump Control Module on the driver's side frame rail, often behind the rear wheel well liner or above the spare tire. Visually inspect and physically check if the main electrical connector (C433 or C4033) is fully seated and locked. Wiggle the connector to see if it causes any change.
   Typical fix: Firmly reseat the connector until it clicks. If the lock is broken, secure the connector with a heavy-duty zip tie 🎬 Watch: How to fix a loose fuel pump connector as a common and effective field repair. Clear the codes and test drive.
   Est. part cost: $0-$5
2. Corroded or Damaged Wiring/Pins 🟡 Medium Probability The FPCM is located on the vehicle's frame, exposing it to moisture, road salt, and debris which can lead to corrosion over time. Wires in the harness can also chafe against the frame or each other, eventually breaking inside the loom.
   How to confirm: Disconnect the FPCM connector and inspect the pins on both the module and the harness side for any signs of green or white corrosion, pushed-out pins, or bent pins. As described by an owner on an F-150 forum, it may be necessary to strip back the wire loom to find corroded or broken wires that aren't visible at the connector.
   Typical fix: Clean corroded pins with an electrical contact cleaner. If pins are severely damaged or pushed out, a new connector pigtail (harness repair kit) may be needed. Damaged wires must be repaired by splicing in a new section with heat-shrink butt connectors.
   Est. part cost: $20-$50
3. Failed Fuel Pump Control Module (FPCM) ⚪ Low Probability → Shop Fuel Pump While less common than the wiring issue on this platform, the module itself can fail electronically due to heat, vibration, or internal component failure. A forum user with a 2013 Expedition fixed their U0109 code by replacing the module after cleaning the connector didn't work.
   How to confirm: After confirming the wiring, connector, and grounds (G403/G406 for Expedition/Navigator) are all good, the module itself becomes the primary suspect. This is often a process of elimination. A bi-directional scan tool may be able to directly test the module's response, but this is typically a last step.
   Typical fix: Replace the Fuel Pump Control Module. On this vehicle, it is a plug-and-play part that does not require programming. It is held on by two bolts.
   Est. part cost: $150-$400

Rare But Worth Checking

• Blown Fuse: Always a quick and easy check. A short circuit in the wiring could blow the fuse that supplies power to the FPCM, causing it to go offline. Check the owner's manual for the location of the fuel pump or FPCM fuse in the power distribution box.
• Faulty Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) This is very rare. The PCM is the main computer, and if its internal communication drivers fail, it can trigger U-codes for various modules. This should only be considered after all other possibilities, including extensive wiring checks, have been exhausted.

Diagnosis Steps

1. Read all diagnostic trouble codes (DTCs) with an OBD-II scanner. Note any other codes present with U0109, 🎬 Watch: Diagnosing U0109 and P0627 codes on a Ford especially P025A, P0627, or P008A.
2. Check the fuse for the Fuel Pump Control Module in the vehicle's power distribution box. Replace if blown.
3. Locate the FPCM. On the 2018-2024 Expedition, it is mounted to the frame rail on the driver's side, accessible by removing the rear wheel well liner or by looking above the spare tire. Crucially, you must visually verify its location, as some models may have the module integrated into the in-tank fuel pump assembly.
4. Inspect the main electrical connector (C433 or C4033) going into the FPCM. Ensure it is fully seated and the locking tab is engaged. A loose connection is the most common cause. If it's loose, push it on firmly until it clicks.
5. If the connector's locking tab is broken, secure it tightly with a zip tie. This is a very common and effective repair.
6. If the connection is secure, disconnect it. Carefully inspect all pins and terminals on both the module and harness for corrosion (green/white powder), moisture, or damage. Clean with electrical contact cleaner if necessary.
7. Follow the wiring harness from the connector as far as you can. Look for any signs of chafing, cuts, or rodent damage. Some owners have found broken wires inside the protective loom, requiring careful inspection.
8. Check the relevant ground points for the FPCM, which TSB SSM 52483 identifies as G403 and G406 for the Expedition/Navigator. Ensure they are clean, tight, and free of corrosion.
9. If the wiring, connector, and grounds are in good condition, the next most likely cause is a failed FPCM. Replacing the module is the next step.
10. If the problem persists after replacing the FPCM, a more in-depth diagnosis of the CAN bus network and PCM is required, which may necessitate professional service.

Parts You'll Likely Need

• Fuel Pump Control Module (OEM #HL3Z-9D370-B) — If the wiring and connection are confirmed to be good, the module itself is the likely point of failure. This is the correct part for 2018-2021 models; always verify by VIN for later years.
  Trusted brands: Motorcraft, Dorman
  OEM price range: $200-$400
  Aftermarket price range: $150-$250
• FPCM Connector Pigtail (OEM #JL1Z-14A411-B) — Needed if the original connector housing or pins are damaged beyond repair from corrosion or physical stress. This allows you to splice a new, clean connector onto the existing harness.
  Trusted brands: Motorcraft
  OEM price range: $20-$40
  Aftermarket price range: $15-$30
• Zip Tie — A heavy-duty zip tie is often used to secure the FPCM connector if the plastic locking tab has broken, preventing it from vibrating loose again. This is a highly common, real-world fix.
  Trusted brands: Any
  OEM price range: $0.10
  Aftermarket price range: $0.10

Related Codes That Often Appear With This One

• P0627 — Stands for 'Fuel Pump 'A' Control Circuit/Open'. This code often appears with U0109 because the communication loss leads to an open circuit condition being detected by the PCM. (Cited in TSB SSM 52483)
• P025A — Stands for 'Fuel Pump Module Control Circuit/Open'. This is another code that points directly to the FPCM circuit and is frequently logged alongside U0109. (Cited in TSBs SSM 52483, SSM 51306, SSM 49618, SSM 50661)
• P008A — Stands for 'Low Pressure Fuel System Pressure - Too Low'. If the FPCM stops working due to communication loss, fuel pressure will drop, triggering this code. (Cited in TSBs SSM 52483, SSM 51306, SSM 50661)

Technical Service Bulletins (TSBs) & Recalls

• SSM 52483: Notes U0109 with other fuel codes, advises checking for intermittent or partial disconnect of the fuel harness at connector C433/C4033 and checking grounds G403/G406.
• SSM 51306: Cites U0109 and other codes, points to intermittent harness disconnect at the fuel pump control module.
• SSM 49618: Specifically mentions U0109 and P025A due to a harness disconnect at the fuel pump control module, connector pin issues, or bad grounds.
• SSM 50661: Lists U0109 with other DTCs, attributing the cause to a potential harness disconnect at the FPCM.

Platform-Specific Known Issues

• Multiple Technical Service Bulletins (SSM 52483, 51306, 50661, 49618) have been issued by Ford for the 2018-2024 Expedition (and other models) specifically for code U0109, often accompanied by codes like P025A, P0627, and P008A. The bulletins consistently point to an 'intermittent or partial disconnect of the harness to the fuel pump control module' as the primary cause to investigate before replacing any parts. TSB SSM 52483 specifically names connector C433/C4033 and grounds G403/G406 as the points to inspect on an Expedition/Navigator.

Mechanic-Grade Diagnostic Values

• CAN Bus Network Resistance — expected: ~60 Ohms. Failure: A reading of ~120 Ohms indicates an open circuit in one of the two terminating resistors or the wiring to it. A reading near 0 Ohms indicates a short between the CAN High and CAN Low wires.
• CAN High Voltage (Key On, Engine Off) — expected: Fluctuates between 2.5V and 3.5V. Failure: A steady voltage, 0V, or battery voltage indicates a network fault (short to ground, short to power, or open circuit).
• CAN Low Voltage (Key On, Engine Off) — expected: Fluctuates between 2.5V and 1.5V. Failure: A steady voltage, 0V, or battery voltage indicates a network fault (short to ground, short to power, or open circuit).
• FPCM Power Supply Pin Voltage — expected: 11.5V - 12.5V (or battery voltage). Failure: Low or no voltage indicates a problem with the power supply circuit (fuse, relay, or wiring) before the module itself.

Scan Tool Commands That Help

• Ford IDS (Integrated Diagnostic System): Network Test — This is the primary function for a U-code. It 'pings' every module on the network and reports which ones fail to respond. It can also detect and count 'missed messages' in real-time, which is invaluable for catching intermittent connection problems by wiggling the harness.
• Ford IDS (Integrated Diagnostic System): KOEO (Key On, Engine Off) On-Demand Self Test — To command the PCM and other modules to check their circuits for faults that are present at the time of the test. This can help confirm if the communication loss is a hard fault.
• Advanced Bi-Directional Scanner (e.g., Thinkdiag): Actuation Test - Fuel Pump — This command allows the user to directly turn the fuel pump on and off via the scan tool. If the pump runs during this test, it confirms the FPCM, pump, and wiring between them are likely functional, pointing the diagnosis more toward the communication line to the PCM.

Wiring & Ground Locations

• G403 / G406 — TSB SSM 52483 identifies these as the relevant grounds for the FPCM on the Expedition/Navigator. Frame grounds are typically located on the frame rail near the component they serve. For the FPCM, look for a wire bolted to the frame near the module's location above the spare tire.. A loose or corroded ground can cause the module to lose power or create electrical noise, interrupting communication and setting a U0109 code.
• C433 / C4033 — This is the main electrical harness connector that plugs into the Fuel Pump Control Module (FPCM).. This connector is the single most common point of failure for this code on this vehicle, due to becoming loose, corroded, or having a broken locking tab.
• Inertia Fuel Shutoff Switch — Typically located in the passenger-side kick panel area.. The inertia switch cuts power to the fuel system in a collision. While it doesn't directly cause a communication code, if it's faulty or partially tripped, it can interrupt power to the FPCM, causing it to go offline and trigger a U0109 code.

Real Owner Repair Stories

• YouTube channel 'Just a Dude' (2018 Ford F-250 (platform mate) with 6.2L Gas Engine) — Random crank-no-start, which became progressively worse until it would not start at all. Codes U0109 and P025A were present.
  ❌ Tried (didn't work) Replacing the Fuel Pump Control Module (FPCM).
  ✅ What actually fixed it The fuel pump relay, which is integrated (non-serviceable) into the fuse box/BCM, had failed. The technician diagnosed this by confirming there was no 12V power on the supply wire at the FPCM connector. He wired in an external relay as a fix.
• YouTube channel 'Tony's Cool Tools' (2014 Ford Escape (shares similar electronic architecture)) — Check engine light with codes U0109 and P025A, particularly after remote start attempts.
  ❌ Tried (didn't work) Replacing the vehicle battery., Replacing the Fuel Pump Control Module (FPCM).
  ✅ What actually fixed it The vehicle had stored crash data in the airbag module (RCM). After a technician reset the airbag module, the U0109 and P025A codes disappeared and did not return. The theory is the faulty airbag module was causing interference or errors on the CAN bus network, preventing the PCM from communicating with the FPCM.

"I Checked Everything" — The Actual Cause

• In the context of a U-code, this pattern means 'all wiring looks good, but the problem was elsewhere.' A documented case on a 2018 F-250 with U0109 showed that while the harness from the fuse box to the FPCM was intact, the internal fuel pump relay inside the fuse box itself had failed, cutting off power. A visual inspection of the harness would miss this.
• Another case showed that all wiring and voltages for the fuel pump circuit tested normal, but the root cause was interference on the CAN bus from a completely separate module (the airbag module) that had stored crash data.

When the Usual Fixes Don't Work

• While the vast majority of U0109 codes on this platform are caused by the FPCM connector, there are confirmed cases where the fix was something else entirely. In one instance on a 2018 F-250, the problem was a failed, non-serviceable fuel pump relay inside the main fuse box, which prevented power from ever reaching the FPCM. In another unusual case, stored crash data in the airbag module was causing CAN bus network interference, which was resolved by resetting that module. These cases highlight the need to confirm power at the FPCM and check the entire vehicle network if the simple connector fix doesn't work.

OEM Part Supersession History

• HL3Z-9D370-A → HL3Z-9D370-B — Part revision by manufacturer. The new part is the standard replacement.
• AU5Z-9D370-J → N/A for this vehicle
  Heads up: This part number is for older Ford models (approx. 2009-2014) and is not correct for the 2018-2024 Expedition, despite being a common result in searches. Using this part will likely result in failure.

Model Year Variations Within This Range

• 2018-2024: While many Expeditions in this range have an external FPCM on the frame rail, some configurations may have the module integrated into the fuel pump assembly inside the fuel tank. A visual inspection is mandatory before ordering parts to confirm if you have an external, frame-mounted module or an internal one.