1. Check the battery. Make sure the battery is properly connected and that the terminals are clean and free of corrosion. If the battery is old or damaged, it may need to be replaced.
2. Check the battery cables. Make sure the battery cables are properly connected and that they are not loose or damaged. If the cables are corroded, they may need to be cleaned or replaced.
3. Check the charging system. The charging system consists of the alternator, voltage regulator, and wiring. If any of these components are faulty, they can cause the battery voltage to drop and trigger an error code 12. To test the charging system, you can use a voltmeter to measure the voltage at the battery terminals. The voltage should be between 13.5 and 14.5 volts when the engine is running.
If you are unable to troubleshoot and resolve the issue yourself, it is recommended to take your vehicle to a qualified mechanic for further diagnosis and repair.
