Controller shows E-20, generator stops, no obvious mechanical problem

Safety: Disable automatic start and isolate AC power. Do not attempt to open or repair the controller PCB yourself.

• Power cycle controller: Turn off DC power to the controller (disconnect battery negative or controller fuse) for 1–2 minutes, then restore power and check if E-20 clears.
• Check controller power supply: Verify stable DC voltage at the controller power terminals. Inspect fuses and wiring for loose connections.
• Inspect environment: Ensure the controller is not exposed to excessive moisture, vibration, or heat that could cause intermittent faults.
• Firmware update: If available and you are trained, update the controller firmware using CAT-approved tools and procedures.

If E-20 persists after power cycling and environmental checks, the controller likely needs replacement or repair by an authorized CAT service center.