U3035 signals that a vehicle module received an invalid authentication signal from another control unit, indicating a failure in the handshake that verifies data integrity on the network.
Corroded, loose, or damaged CAN‑bus wires or connectors can corrupt the authentication signal exchange between modules.
These modules generate the authentication signal; internal faults can cause it to transmit invalid data.
A defective key transponder or antenna can prevent the correct authentication code from being received.
A failing PCM can misinterpret or send authentication signals, but this is uncommon and should be considered only after other causes are ruled out.
Corrupt software in a control module may produce invalid authentication signals; reprogramming may be required.
Replacing the PCM is rarely necessary; the code is usually caused by wiring or a faulty authentication module, not the PCM itself.
A low battery can affect communication reliability but does not directly cause an authentication failure; the code points to a specific signal problem.
The primary effect is that the vehicle may not start or may shut off, but it does not impact driving safety once the engine is running.
Any qualified technician who can perform CAN‑bus diagnostics can identify and repair the underlying cause.