Lexus ES300 electrical systems function with jump start but fails to start, new battery not retaining charge on Lexus ES300

Some Lexus ES300 owners report experiencing starting issues even after jump-starting, with new batteries failing to retain their charge. These problems may stem from underlying battery issues or a malfunctioning charging system. Additionally, some owners find that a defective starter relay or control unit can contribute to their vehicle's starting difficulties. An activated theft deterrent system is also reported to prevent the Lexus ES300 from starting, causing frustration for owners. In some cases, simply replacing the key fob battery resolves the issue, but persistent problems may indicate a more serious concern. Furthermore, issues with the charging system, such as a faulty alternator or voltage regulator, can lead to the new battery not being charged properly. To resolve these issues, it is advisable for owners to have their vehicles diagnosed by a professional mechanic and to check all related components for malfunctions.