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DTC codes / U01xx · Lost communication with a control module / U016C

U016CLost Communication With Fuel Pump Control Module B

U016C is a communication fault where the engine control module (ECM) or another network module has lost the controller area network (CAN) signal from the fuel pump control module B, a dedicated module that regulates fuel pump speed and voltage. The ECM sets this code after repeated failed attempts to receive data from that module, indicating a break in the communication path rather than a direct fuel pump failure.

SystemNetwork
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaLost communication with a control module

Symptoms you may notice

  • Illumination of the malfunction indicator lamp (MIL) on the dashboard.
  • Often no symptoms besides the warning light, especially if the fuel pump control module B defaults to a fixed output.
  • Engine may crank but fail to start or stall shortly after starting due to loss of fuel pump control.
  • Intermittent engine hesitation or reduced power under load if the module signal drops momentarily.
  • Fuel pump may run continuously or not at all, leading to a no-start condition or fuel pressure irregularities.
  • Other dashboard warnings or communication-related codes may appear if the fault lies on a shared network segment.

Common causes, most likely first

  1. Damaged or corroded wiring harness between the fuel pump control module B and the ECM or network backbone.
  2. Failed fuel pump control module B itself, often due to internal circuit faults or water intrusion.
  3. Blown fuse or poor ground connection supplying power to the fuel pump control module B.
  4. Loose or corroded connector pins at the module, ECM, or inline harness connectors.
  5. CAN bus wiring fault such as an open circuit, short to ground, or short to voltage on the communication lines.
  6. Low battery voltage or a failing charging system causing modules to drop offline intermittently.
  7. Aftermarket accessories or poor previous repairs that disturbed the network wiring or added electrical noise.

How to diagnose and fix it

  1. Verify battery voltage and charging system output; a weak battery can cause communication codes without a hard fault.
  2. Inspect and test the fuse and ground circuits for the fuel pump control module B using a multimeter and wiring diagram.
  3. Perform a visual inspection of the module connector and harness for corrosion, chafing, or loose pins, then clean and reseat connectors.
  4. Use a scan tool to check for other communication codes and confirm whether the module B is completely offline or intermittent.
  5. Measure CAN bus voltage and resistance at the module connector to detect open or shorted communication lines.
  6. If wiring and power are good, substitute a known-good fuel pump control module B and clear the code to see if communication returns.
  7. After repair, clear all codes and perform a road test with live data monitoring to confirm the module stays online under load.

What most technicians miss on U016C

  • A failed fuel pump control module B often sets no drivability symptoms because the pump may default to full speed, so the warning light is the only clue.
  • Corrosion inside the module connector is a frequent cause that looks like a failed module but is fixed by cleaning and reseating the pins.
  • The code can be set by a weak battery or a poor ground that momentarily drops the module offline, so always load-test the battery before replacing parts.
  • On some vehicles, the fuel pump control module B shares a network segment with other modules, so a single wiring fault can set multiple U-codes that point away from the real culprit.
  • Aftermarket remote starters or alarm systems spliced into the harness can introduce communication faults that mimic a failed module.

Can I keep driving with U016C?

If the engine starts and runs normally, you can drive to a repair shop, but avoid hard acceleration and long trips because the fuel pump may lose control at any time. If the engine cranks without starting or stalls repeatedly, do not drive and have the vehicle towed to prevent a dangerous breakdown.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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