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

What's Unique About the 2018-2024 Ford EXPLORER

This issue is extremely common across many Ford models from this era, including the Explorer, F-150, Expedition, and Lincoln Aviator/Navigator. Ford has released numerous Technical Service Bulletins (TSBs) that point directly to an intermittent or partial disconnect of the electrical harness to the Fuel Pump Control Module. This indicates a known weakness in the connection's design or assembly, making a wiring check the absolute first step before considering part replacement. Forum discussions are filled with owners who have fixed this issue simply by reseating the connector and adding a zip tie for security.

Diagnostic Flowchart

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

Generation note: This year range covers two generations of the Explorer: the fifth generation (2018-2019) and the sixth generation (2020-2024). The root cause, a poor harness connection to the Fuel Pump Control Module, is documented in TSBs that apply to both generations, indicating a persistent issue across the platform change. TSBs specify different connector and ground point designations for each generation.

Symptoms You May Notice

• Check Engine Light (MIL) illuminated
• Wrench light illuminated on the dashboard
• Engine cranks but does not start
• Engine stalls unexpectedly, especially at idle or under load
• Hesitation or loss of power while driving
• No audible 'whine' from the fuel pump when the key is turned to the 'ON' position
• Intermittent starting issues

Most Likely Causes

1. Loose or Intermittent Connection at the FPCM Harness 🔴 High Probability Multiple Ford TSBs (including SSM 52482, SSM 51306, SSM 49618, SSM 52483) explicitly state this is the most likely cause due to a partial disconnect of the harness connector. The connector's locking tab can be weak or not fully engaged, leading to intermittent contact from road vibrations.
   How to confirm: Locate the FPCM. For 2018-2019 models, inspect connector C3239. For 2020-2024 models, inspect connector C4033. The module is typically on the driver's side, accessible from underneath the vehicle, sometimes behind a wheel well liner. Physically check if the connector is fully seated. Wiggle the connector to see if it induces the fault or resolves it temporarily.
   Typical fix: Ensure the connector is fully seated and locked. Listen for a click. Many owners and technicians add a zip tie around the connector and module as a secondary measure to prevent it from backing out. Clean the terminals with electrical contact cleaner before reseating.
   Est. part cost: $0-$5
2. Damaged Wiring or Corroded Terminals/Grounds 🟡 Medium Probability The TSBs also mention connector pin push-outs, damaged pins/terminals, or loose/corroded grounds as potential causes. The FPCM's location under the vehicle exposes it to moisture and road salt, leading to corrosion on connector pins or the ground connection. There are also owner reports of wires breaking inside the loom near the FPCM.
   How to confirm: Disconnect the FPCM connector and inspect the pins and terminals for corrosion (green or white powder), spreading, or being pushed out of the connector body. Inspect the relevant ground point (G302 for 2018-2019, G407 for 2020-2024) for corrosion and tightness.
   Typical fix: Clean corroded terminals with a small wire brush or electrical contact cleaner. Apply dielectric grease to the connector before reassembly to prevent future moisture intrusion. Reseat any pushed-out pins. If wiring is broken, it will need to be repaired, often by splicing in a new section of wire or a connector pigtail.
   Est. part cost: $10-$75
3. Failed Fuel Pump Control Module (FPCM) ⚪ Low Probability → Shop Fuel Pump While the module can fail, it is far less common than the connection and wiring issues documented by Ford. It is frequently replaced unnecessarily when the actual fault is a poor connection.
   How to confirm: This should only be suspected after all wiring, connector, and ground issues have been definitively ruled out. Diagnosis involves using a scan tool to attempt communication and a multimeter to verify power, ground, and CAN bus signals at the module connector.
   Typical fix: Replace the Fuel Pump Control Module. On some platforms, this may require programming with a tool like FORScan, while others may be plug-and-play.
   Est. part cost: $70-$200

Rare But Worth Checking

• Blown Fuse: A blown fuse for the fuel pump or FPCM circuit will cause a loss of power and communication. It's a quick and easy check. For 2018-2019 models, check the 30A MCASE fuse at position 63 in the under-hood fuse box. For 2020-2023 models, check the 30A fuse at position 4.
🎬 Watch: How to locate and test your Explorer's fuel pump fuse
• Failed Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) This is extremely rare. The PCM is the last component to suspect, and this diagnosis should only be made by a professional after all other possibilities have been exhausted.

Diagnosis Steps

1. Read all Diagnostic Trouble Codes (DTCs) from the PCM and other modules. Note all codes present, especially P0627, P025A, P008A, or P00C6.
2. Locate the Fuel Pump Control Module (FPCM). On the 6th Gen Explorer (2020+), it is often found on the bottom side of the left front floor panel, accessible from underneath the vehicle. On the 5th Gen (2018-2019), it is typically on the driver's side frame rail, sometimes behind the rear wheel well liner.
3. Visually inspect the FPCM electrical connector for being loose, disconnected, or damaged. Per multiple TSBs, this is the most likely cause.
4. Ensure the connector is fully seated and the locking tab clicks into place. Clear codes and re-test. Consider adding a zip tie for extra security, a widely reported successful fix.
5. If the code returns, disconnect the battery. Disconnect the FPCM connector and inspect the pins and terminals in both the harness and the module for corrosion, moisture, or damage (bent or pushed-out pins).
6. Inspect the ground wire connection for the FPCM. For 2018-2019 models, this is G302. For 2020-2024 models, it is G407. Ensure it is clean, tight, and free of corrosion.
7. Check the fuse for the fuel pump circuit in the under-hood fuse box.
8. If all connections, grounds, and fuses are good, the next step is to use a multimeter to test for power, ground, and CAN bus network signals at the FPCM connector. This requires a wiring diagram and knowledge of electrical testing.
9. Only after confirming the wiring and signals are correct should the FPCM itself be condemned and replaced.

Parts You'll Likely Need

• Fuel Pump Control Module (OEM #FU5Z-9D370-C (example, verify by VIN)) — This is the part to replace ONLY after verifying all wiring, connections, and grounds are good. It is often replaced when the actual fault is a bad connection.
  Trusted brands: Motorcraft, Dorman
  OEM price range: $120-$200
  Aftermarket price range: $70-$150
• FPCM Connector Pigtail (OEM #Motorcraft WPT-1275 (example, verify by VIN and connector pin count)) — If the connector housing or terminals are damaged or corroded beyond cleaning, replacing the connector itself by splicing in a new pigtail is the proper repair.
  Trusted brands: Motorcraft, Standard Motor Products, Dorman
  OEM price range: $30-$60
  Aftermarket price range: $15-$40
• Zip Tie — A common and effective DIY solution to add security to the FPCM connector to prevent it from vibrating loose, which is the root cause in many cases.

Related Codes That Often Appear With This One

• P0627 — Relates to 'Fuel Pump A Control Circuit / Open'. This code is often stored alongside U0109 because if the FPCM isn't communicating, the PCM also sees an open control circuit.
• P025A — Relates to 'Fuel Pump Module A Control Circuit / Open'. Similar to P0627, this code is triggered when the PCM detects an open circuit to the FPCM, which is a direct consequence of the lost communication.
• P008A — Relates to 'Low Pressure Fuel System Pressure - Too Low'. If the FPCM isn't communicating or powered, it can't run the fuel pump, leading to low fuel pressure.
• P00C6 — Relates to 'Fuel Rail Pressure Too Low - Engine Cranking'. This is another low fuel pressure code that can result from the FPCM not operating correctly.

Technical Service Bulletins (TSBs) & Recalls

• SSM 52482: For 2020-2024 Explorer/Aviator, advises checking fuel pump circuits and connectors C433/C4033 and ground G407.
• SSM 51306: For various 2020-2023 Fords including Explorer, points to an intermittent or partial disconnect of the harness to the FPCM.
• SSM 50841 / SSM 49618: For 2018-2022 models including Explorer, specifies checking the FPCM connector (C3239 for 18-19, C4033 for 20+) and grounds (G302 for 18-19, G407 for 20+) for a secure connection.
• SSM 52483: For 2018-2019 Explorer, reiterates checking for a harness disconnect, damaged pins, and ground G302.

Platform-Specific Known Issues

• Ford has issued multiple Technical Service Bulletins regarding this code and its companions (P0627, P025A, etc.) on the Explorer and other models. The consistent advice is to check for an intermittent or partial disconnect of the harness to the fuel pump control module, as well as checking for damaged pins or corroded grounds before replacing parts.
• TSB SSM 52482 specifically covers 2020-2024 Explorer/Aviator models and points to checking FPCM connector C4033 and ground G407.
• TSB SSM 52483 covers 2018-2019 Explorer models (among others) and points to checking FPCM connector C3239 and ground G302.

Mechanic-Grade Diagnostic Values

• CAN Bus Network Resistance — expected: Approximately 60 Ω (with battery disconnected). Failure: A reading significantly higher than 60 Ω (like 120 Ω) may indicate a problem with a terminating resistor or module. An open circuit (O.L.) indicates a broken wire.
• FPCM Power Supply Voltage — expected: 11.5 - 12.5 V (Key On). Failure: Low or no voltage indicates a problem with the fuse, relay, or wiring supplying power to the module, not the module itself.
• FPCM Output to Fuel Pump Resistance — expected: A few ohms (e.g., 1-2 Ω). Failure: An open circuit (O.L.) suggests a failed fuel pump or a break in the wiring between the FPCM and the pump. This helps differentiate a pump failure from a module/communication failure.

Hidden / Shadow Codes Worth Checking

• U0109 / P025A: These codes may not always appear as standard, continuous memory DTCs. They can sometimes only be retrieved by performing a Key On Engine Off (KOEO) self-test with a capable scan tool like FORScan or the dealer's IDS. (see via Run the KOEO or On-Demand Self-Test using a Ford-specific scan tool. A basic OBD-II reader might not show these codes if the Check Engine Light is not currently on.)

Scan Tool Commands That Help

• Ford IDS / FORScan: Network Test — This function actively 'pings' every module on the CAN bus. A 'fail' response for the FPCM definitively confirms a communication loss, helping to isolate the problem.
• Ford IDS / FORScan: FPCM On-Demand Self-Test — This command specifically queries the FPCM for internal faults. This can help determine if the module itself has an internal error, even if it's intermittently communicating.
• Bi-directional Scan Tool: Fuel Pump Command (On/Off) — After verifying power and ground, a technician can use this command to directly order the FPCM to turn the fuel pump on. If the pump runs, it confirms the FPCM, pump, and wiring between them are likely good, pointing the diagnosis back towards the communication lines to the PCM.

Wiring & Ground Locations

• G407 — Applicable to 2020-2024 Explorer/Aviator models. The exact location requires a service manual diagram, but it is the primary ground for the FPCM circuit.. A loose or corroded G407 will cause a loss of power or intermittent operation of the FPCM, directly leading to a U0109 code. TSBs specifically call for its inspection.
• G302 — Applicable to 2018-2019 Explorer models. This is the main ground point for the FPCM on the fifth-generation platform.. Similar to G407 on the newer models, a fault at this ground point will interrupt FPCM operation and trigger a communication loss code.
• C4033 — The main harness connector at the FPCM for 2020-2024 models. Located underneath the vehicle, often on the driver's side floor pan.. This is the single most common failure point. TSBs repeatedly identify a partial or intermittent disconnect here as the primary cause of U0109.
• C3239 — The main harness connector at the FPCM for 2018-2019 models. Typically found on the driver's side frame rail.. This is the equivalent of C4033 for the fifth-generation Explorer and is the most likely source of the problem for these model years.
• C1147 / C3136 — Inline harness connectors for 2020-2024 models, located between the PCM and the FPCM.. TSB SSM 52482 specifically calls out these inline connectors as potential points of failure. A problem here would be missed by only inspecting the FPCM connector itself.

Real Owner Repair Stories

• Ford Expedition Forum user 'xFred12' (2013 Expedition (platform shares similar FPCM design principles)) — Wrench light, no codes on a standard scanner. FORScan revealed U0109.
  ❌ Tried (didn't work) Replacing the Throttle Body., Cleaning the existing FPCM connector with electrical contact cleaner.
  ✅ What actually fixed it Replacing the Fuel Pump Control Module (FPCM), which was located behind the driver's side rear wheel well liner. The user noted that simply cleaning the connection was not enough and the module itself had failed.
• Various automotive forums and YouTube videos (Multiple Ford/Lincoln models with loose connectors) — Intermittent electrical faults, codes appearing after hitting bumps.
  ❌ Tried (didn't work) Replacing sensors or modules when the connector was the actual issue.
  ✅ What actually fixed it Securing a loose electrical connector with a zip tie. The zip tie is wrapped around the connector and the component body, applying constant pressure that prevents the plug from vibrating loose where the locking tab has failed or is weak. This is a widely accepted field repair for this type of connection failure.

"I Checked Everything" — The Actual Cause

• While not a smoke test scenario, a similar diagnostic dead-end occurs when the FPCM connector and ground appear perfect. In these cases, the fault can be a broken wire within the harness running along the vehicle's frame. A technician on a 2021 F-150 with U0109 traced the power supply wire from the fuse box and found it was good at an intermediate connector but dead at the FPCM connector, confirming an open circuit (broken wire) somewhere in the final wiring section to the module.

When the Usual Fixes Don't Work

• While the overwhelming majority of U0109 cases on this platform are caused by the harness connection, it is not the only possibility. A documented repair on a similar Ford platform showed that even after cleaning the connector, the U0109 code persisted. The final fix was to replace the Fuel Pump Control Module itself, indicating an internal failure of the module. This serves as a reminder to not automatically condemn the wiring if a thorough inspection and re-seating of the connector does not resolve the issue, and to proceed with electrical testing of the module's power, ground, and output signals.

OEM Part Supersession History

• FU5Z-9D370-B → FU5Z-9D370-C — Part revisions are common to address design flaws, improve durability, or change suppliers. The move from -B to -C likely represents an internal update to the module's electronics or housing.
  Heads up: While the -C version is the current replacement for the -B, it is always critical to verify the correct part number for your vehicle's specific VIN. Using the wrong module, even if it physically connects, can result in a no-start condition or other communication errors.

Model Year Variations Within This Range

• 2020-2024: In addition to the main FPCM connector (C4033) and ground (G407), TSB SSM 52482 specifically advises technicians to also inspect inline harness connectors C1147 and C3136 for damage or a poor connection. This detail is not present in TSBs covering the earlier 2018-2019 models.