U0494 is set when the vehicle’s communication network detects invalid or out‑of‑range data coming from the Digital Audio Control Module (DACM). This indicates a fault in the DACM’s message transmission on the CAN bus, such as corrupted data, missing signals, or a module that is not responding correctly.
The DACM itself may have internal hardware or firmware faults that cause it to send malformed messages on the CAN bus.
Damaged, corroded, or loose wiring harnesses and connectors between the DACM and the CAN bus can interrupt or corrupt the data stream.
Bus‑wide problems such as high resistance, short to power/ground, or termination issues can cause the DACM’s messages to be interpreted as invalid.
Out‑of‑date or corrupted module firmware can result in the DACM transmitting data that fails validation checks.
Inadequate voltage or poor ground connections can cause the module to operate erratically and send invalid data.
While highly unlikely, a fault in the powertrain control module’s CAN transceiver could prevent proper reception of DACM messages; this should be considered only after all other causes are ruled out.
No. The PCM/ECM is rarely at fault for this code; the issue almost always lies with the DACM, its wiring, connectors, or the CAN bus. Replace the PCM only after all other possibilities have been exhausted.
Clearing the code may turn off the warning, but if the underlying communication fault remains, the symptom (loss of audio or other network issues) will likely return.
Yes. Corrupted or outdated DACM firmware can cause invalid messages; updating or reflashing the module often resolves the code.
Antenna or speaker wiring faults do not cause U0494, as the code pertains to data communication from the DACM, not audio output paths.