U010A

Lost Communication With Exhaust Gas Recirculation Control Module A

U010A is a generic OBD-II network diagnostic trouble code: Lost Communication With Exhaust Gas Recirculation Control Module A. 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
U010A
Group
Network
System
EGR
Severity
Warning (MIL on, possible limp mode)
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What U010A means

U010A is set when the primary control module (typically the ECM or PCM) can no longer receive or exchange messages with the Fuel Pump Control Module (FPCM) over the vehicle's serial data bus. Modern returnless fuel systems rely on a dedicated FPCM to regulate pump speed and fuel pressure; if communication is lost, the controlling module cannot command appropriate pump output for current engine demand.

The fault is detected when the expected CAN or LIN message from the FPCM is absent for a calibrated timeout period. Because fuel delivery cannot be confirmed, many calibrations substitute a fixed maximum pump duty cycle or a conservative default, which may result in rich running, elevated fuel pressure, or -- in protective strategies -- reduced power or a no-start condition depending on the vehicle's failsafe logic.

Common root causes are wiring faults (opens, shorts, or corrosion) on the bus circuit between the ECM and FPCM, a blown supply fuse or missing ground for the FPCM, and failed or sleeping FPCM hardware. Always verify bus termination resistance and supply voltages at the FPCM connector before condemning the module itself.

Common causes

Most-frequently reported root causes when U010A is logged.

  • 1
    Open or short circuit in the CAN or LIN data bus wiring between ECM and FPCM.
  • 2
    Corroded, backed-out, or spread terminal pins at the FPCM harness connector.
  • 3
    Blown fuse or failed relay supplying ignition voltage to the FPCM.
  • 4
    Poor or missing chassis/body ground connection for the FPCM.
  • 5
    Failed Fuel Pump Control Module (internal hardware fault).
  • 6
    Excessive bus load or another module holding the bus dominant and blocking FPCM messages.
  • 7
    ECM software or calibration mismatch causing the bus ID to be unrecognised.

Symptoms drivers notice

MIL (Check Engine lamp) illuminated.
Engine may crank but fail to start or stall shortly after startup.
Reduced engine power or hesitation under heavy throttle demand.
Fuel pump audible priming noise absent when ignition is switched on.
Other fuel-system-related DTCs stored alongside U010A.

How to diagnose U010A

A typical diagnostic flow when this code is present.

  1. 1
    Connect a scan tool and record all stored DTCs and freeze-frame data before clearing codes.
  2. 2
    Check for Technical Service Bulletins (TSBs) for the vehicle related to FPCM communication or software updates.
  3. 3
    Inspect the FPCM supply fuse and relay; measure battery voltage and ground integrity at the FPCM connector with ignition on.
  4. 4
    Measure bus termination resistance (typically 60 ohms across CANH/CANL with both modules unplugged) to verify no open or short on the data bus.
  5. 5
    Use a scan tool to observe live CAN bus traffic or FPCM parameter IDs; confirm whether the FPCM appears on the network at all.
  6. 6
    Inspect the harness between the ECM and FPCM for chafing, moisture intrusion, and terminal condition; repair any fault found.
  7. 7
    If all wiring and power circuits are confirmed good, substitute a known-good FPCM and retest.

Related network codes

Frequently asked questions

Can U010A be caused by a weak battery?

Yes. A low or unstable battery voltage during cold starts can cause modules to drop off the bus momentarily, setting a U-code. Fully charge and load-test the battery before diagnosing the FPCM circuit.

Will the engine run at all with U010A active?

It depends on the manufacturer's failsafe calibration. Many vehicles fall back to a fixed pump duty cycle that allows the engine to run at reduced performance; others may prevent starting to protect the fuel system.

Is U010A the same as U0100?

No. U0100 is lost communication with the ECM/PCM itself. U010A specifically identifies the Fuel Pump Control Module as the unresponsive node.

Should I replace the FPCM first when U010A is stored?

No. Module replacement should be the last step after confirming power supply, grounds, and bus wiring are all sound, because wiring faults are far more common than outright module failure.

Disabling U010A in software

RaceTune can permanently disable U010A — 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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