DTC P0620-49: Generator Control Circuit Internal Electronic Failure [11/2021 - 03/2023]: Description

WARNING: This page is about a different car, the 2025 Lexus NX 350, 2024 Lexus NX 350, 2023 Lexus NX 350, and 2022 Lexus NX 350. However, it is still accessible from the selected car via links, so may be relevant.

The alternator performs self-diagnosis of its internal circuits to detect malfunctions (open or short circuits).

The ECM receives the result via LIN communication and stores a DTC.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Warning Indicate	Note
P0620-49	Generator Control Circuit Internal Electronic Failure	All of the following conditions are met (1 trip detection logic): Ignition switch ON. Except during engine cranking. Auxiliary battery voltage is 10.5 V or higher. No malfunction in the LIN communication system. Open or short in EXC circuit, or abnormal waveform for PH circuit.	Generator assembly	Charge warning is displayed	SAE Code: P0620