U010B

Lost Communication With Exhaust Gas Recirculation Control Module B

U010B is a generic OBD-II network diagnostic trouble code: Lost Communication With Exhaust Gas Recirculation Control Module B. It is logged by the engine control unit when the egr monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
U010B
Group
Network
System
EGR
Severity
Warning (MIL on, possible limp mode)
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What U010B means

U010B indicates that the primary control module has lost serial data bus communication with a second or auxiliary Fuel Pump Control Module, designated Module B. This code appears on vehicles equipped with dual fuel pump systems -- for example, vehicles with separate low-pressure lift pumps and high-pressure pump controllers, or dual-tank systems where each tank's pump is managed by its own control node.

The detection logic mirrors that of U010A: the controlling module awaits a periodic CAN or LIN message from the FPCM-B node and sets U010B when that message is absent beyond the calibration timeout. Because the 'B' designation identifies the secondary channel, the primary pump circuit may remain functional, meaning the engine could continue to run in a degraded mode rather than failing to start outright.

Diagnosis should begin by confirming which physical module or circuit is designated 'B' for the specific vehicle, then follow the same power-supply, ground, and bus-integrity checks as for U010A. Shared bus wiring faults can set both U010A and U010B simultaneously; if both codes are present, inspect common wiring sections first.

Common causes

Most-frequently reported root causes when U010B is logged.

  • 1
    Open or short on the data bus segment serving the secondary FPCM (Module B).
  • 2
    Lost power supply or blown fuse for the FPCM-B node.
  • 3
    Poor ground connection specific to the FPCM-B installation location.
  • 4
    Corroded or damaged connector terminals at the FPCM-B harness connector.
  • 5
    Failed FPCM-B module hardware.
  • 6
    Shared wiring fault that simultaneously disrupts both FPCM-A and FPCM-B communication.
  • 7
    Incorrect module configuration or programming after a replacement.

Symptoms drivers notice

MIL illuminated with U010B stored.
Possible reduced fuel delivery from the secondary pump circuit.
Hesitation or stumble under high-demand conditions that require both pump channels.
U010A may be stored alongside U010B if the fault affects the common bus.
No visible drivability issue if the primary pump circuit remains fully operational.

How to diagnose U010B

A typical diagnostic flow when this code is present.

  1. 1
    Record all DTCs and freeze-frame data with a scan tool before any clearing.
  2. 2
    Identify which physical module is designated FPCM-B for the specific vehicle using the service manual.
  3. 3
    Verify battery voltage, ignition-switched supply, and ground at the FPCM-B connector.
  4. 4
    Check bus termination resistance on the segment serving FPCM-B to detect opens or shorts.
  5. 5
    Inspect the harness for damage, especially near the fuel tank where heat and vibration are prevalent.
  6. 6
    Confirm whether FPCM-B appears on the bus using scan tool network node diagnostics.
  7. 7
    If wiring and power are confirmed good, substitute the FPCM-B module and retest.

Related network codes

Frequently asked questions

What does the 'B' suffix mean in U010B?

In SAE J2012 nomenclature, the 'B' suffix denotes the second instance of the same component type -- here a second Fuel Pump Control Module. The exact physical location and role of 'Module B' vary by manufacturer.

Can U010B set without U010A?

Yes. If only the secondary FPCM-B circuit has a fault, U010B will set while U010A remains clear, confirming the primary fuel pump module is still communicating normally.

Is the repair procedure the same as for U010A?

The general diagnostic approach is identical -- check power, ground, and bus wiring before replacing the module -- but you must locate the correct FPCM-B connector and harness path for the specific vehicle.

Will U010B affect my emissions test?

Because U010B is a network communication code it will illuminate the MIL, which will cause a failure on any OBD-II emissions inspection that checks for active DTCs or a lit MIL.

Disabling U010B in software

RaceTune can permanently disable U010B — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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