How do you fix code 12 on Lexus?

Code 12 on a Lexus typically indicates a problem with the vehicle's onboard diagnostic system, often related to a malfunction in the engine control unit (ECU) or a communication issue. To fix it, start by checking the vehicle's battery and fuses for any issues, as a weak battery can cause communication errors. If those are fine, inspect the wiring and connectors related to the ECU for any damage or corrosion. If the problem persists, consider consulting a professional mechanic or using a diagnostic tool for further troubleshooting.