U016C: Lost Communication With Fuel Pump Control Module B

What it means

ECU lost CAN communication with fuel pump control module B. A communication loss with this module breaks any function relying on its data — diagnostic tools may show 'no response' and dependent modules can fall into limp mode.

At a glance

• Usually lights the warning light of the system that lost communication
• Affects emissions; the car can fail an emissions test
• The engine or gearbox may go into limp mode

How it works

Fuel Pump Control Module B controls or coordinates a fuel-pump function and shares operating information with other modules over the CAN network. U016C sets when the reporting module stops receiving expected messages from module B; loss of those messages can disrupt fuel delivery control or related engine functions.

Common causes

Most likely first.

1. Module unpowered
2. Gateway module routing CAN messages incorrectly
3. CAN terminating resistor (120 Ω) drifted out of spec

Symptoms

• Multiple warning lights may illuminate
• Affected modules may go into limp mode or shut down
• Specific functions inoperative depending on module
• Diagnostic tools may show communication faults

How to diagnose it

1. Scan all modules for communication and fuel-system codes, and record freeze-frame data to see whether U016C appeared with a stall, no-start, or other event.
2. Check whether Fuel Pump Control Module B responds to the scan tool and whether the primary fuel-pump control module remains online.
3. Inspect module B’s connectors and harness for damage, corrosion, loose pins, or signs of water entry.
4. Check the module’s fuses, power, and ground using the manufacturer's procedure, since an unpowered module cannot send CAN messages.
5. If its power and ground are good, test the CAN wiring and termination to specification and investigate gateway routing or module failure.

Common fixes

• Clean and secure a loose or corroded module B connector.
• Repair damaged wiring or restore the module’s power or ground supply.
• Repair a CAN bus fault or correct a gateway routing problem.
• Replace Fuel Pump Control Module B if its power, ground, and network circuits test correctly.

Can I keep driving?

Because this fault can affect fuel-pump control, the engine may run poorly, stall, or fail to restart. Avoid driving if the vehicle hesitates or loses power; arrange diagnosis promptly if the fault is active.