U042A: Invalid Data Received From V2X Module

V2X — vehicle-to-everything — is the connectivity technology that lets a vehicle exchange information with other vehicles (V2V), roadside infrastructure such as traffic signals (V2I), pedestrians' devices (V2P), and the wider network (V2N). On vehicles equipped with it, a V2X module handles these short-range and cellular communications and shares relevant data — nearby-hazard alerts, signal timing, cooperative-awareness messages — with other modules over the vehicle's internal network. U042A sets when a receiving module is still hearing from the V2X module, but the data in its messages is invalid: a value is out of range, implausible, or contradicts what other modules see. The link is alive; the content can't be trusted. That is the key difference from a lost-communication code, which means the module has gone completely silent.

Because the fault is bad data rather than a dead bus, the causes cluster around whatever makes the module broadcast wrong information. The V2X module's own software is a frequent culprit — this is a relatively new, software-intensive module, and outdated, corrupted, or mismatched firmware can produce implausible data, especially if the module was replaced or updated without a matching calibration. A failing antenna, GPS/positioning input, or internal fault can also cause it to report values other modules reject. Low system voltage makes module logic unreliable, and corroded connectors or damaged bus wiring can corrupt otherwise-good messages in transit.

Symptoms are usually limited to connectivity features. You may see a check engine or information light, a warning that connected-safety or V2X features are unavailable, or the loss of cooperative alerts that depend on the module. Core driving, braking, and steering are not affected, so U042A is a low-severity, driveable fault. The caveat is that on vehicles that use V2X data to feed driver-assistance or hazard-warning features, those specific convenience/safety-assist functions may be degraded until the fault is fixed — but the vehicle's fundamental controls are unaffected. U042A is frequently a secondary code — read the full list, because a companion telematics, antenna, or software code often names the real root cause.