APC Smart-UPS Error Code F18

APC UPS Critical Fault

Model: Smart-UPS | Code: F18

Applicable Systems
Symmetra LX

Symptoms

The watchdog timer has detected a system hang. The UPS has restarted.

Possible Causes

  • Control firmware hang or infinite loop
  • Watchdog circuit hardware fault

Troubleshooting Steps

  1. Step 1: Check the UPS fault log for the specific watchdog fault sub-code
    Detailed fault information is obtained
  2. Step 2: Contact APC support with the fault code for diagnosis
    Support confirms the faulty component

How to Reset

To reset: Power-cycle the UPS. If the error persists, contact APC support for repair.

Related APC Fault Codes

Source: APC Smart-UPS User Manual, Schneider Electric/APC

Category: UPS