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)
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What U010A means

U010A is set when the ECM or PCM detects that communication with the Exhaust Gas Recirculation Control Module A (EGRCM-A) has been lost over the vehicle's serial data bus, most commonly the CAN bus. On vehicles that use an electronically controlled EGR system with its own dedicated control node, the EGR control module manages the EGR valve position, monitors flow and position feedback, and reports status to the ECM so that recirculated exhaust can be metered to reduce combustion temperatures and NOx emissions.

The DTC sets when the expected periodic message from the EGR control module is absent for a calibrated timeout period. Because the EGR system is emissions-related rather than immediately drivability-critical, most calibrations apply a backup strategy that disables EGR operation on loss of communication. The engine will generally continue to run, but with elevated combustion temperatures, increased NOx output, and possible companion EGR flow or position DTCs.

The most common root cause is a circuit fault that interrupts power or ground to the EGR control module, or an open or short on the data bus itself. Verify supply voltage, ground integrity, and bus wiring at the EGR control module connector before condemning the module, since wiring and connector faults are far more common than internal module failure.

Common causes

Most-frequently reported root causes when U010A is logged.

  • 1
    Open or short circuit in the CAN data bus wiring between the ECM and the EGR control module.
  • 2
    Loss of power or ground supply to the EGR control module.
  • 3
    Blown fuse feeding the EGR control module.
  • 4
    Corroded, backed-out, or spread terminal pins at the EGR control module connector.
  • 5
    Failed EGR control module internal hardware or CAN transceiver.
  • 6
    Heat or vibration damage to the module in its engine-bay mounting location.
  • 7
    Bus fault on a shared segment blocking messages from the EGR control module.

Symptoms drivers notice

MIL (Check Engine lamp) illuminated.
EGR operation disabled with the ECM running a backup strategy.
Scan tool unable to communicate with the EGR control module.
Possible companion EGR flow, position, or performance DTCs stored alongside U010A.
Possible slight increase in combustion temperature or NOx-related emissions.

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 related to EGR control module communication or software updates.
  3. 3
    Inspect the EGR control module supply fuse and measure battery voltage and ground integrity at the module connector.
  4. 4
    Measure bus termination resistance (typically about 60 ohms across CANH/CANL) to check for an open or short on the data bus.
  5. 5
    Use the scan tool to view network node status and confirm whether the EGR control module appears on the bus at all.
  6. 6
    Inspect the harness between the ECM and the EGR control module for chafing, moisture intrusion, and terminal condition.
  7. 7
    If wiring and power circuits are confirmed good, substitute a known-good EGR control module and retest.

Related network codes

Frequently asked questions

Is U010A a serious code?

It is not immediately drivability-critical because the ECM applies a backup strategy when EGR communication is lost, but it is emissions-related and will keep the MIL on until repaired.

Can a weak battery cause U010A?

Yes. Low or unstable battery voltage can cause modules to drop off the bus momentarily and set a U-code, so fully charge and load-test the battery before diagnosing the EGR module circuit.

Will U010A affect fuel economy or emissions?

With EGR disabled the engine can run slightly hotter with higher NOx output, and the lit MIL will cause a failure on any emissions inspection that checks for active DTCs.

Should I replace the EGR control module first?

No. Module replacement should be the last step after confirming power, ground, and bus wiring are 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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