Troubleshooting Tip: 'Power Fault: Error Type 36 (Port is off: Voltage injection into the port)' on FortiSwitch

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Description	This article describes what the 'Power Fault: Error Type 36' error means and how to debug PoE fault errors on FortiSwitch.
Scope	FortiSwitch-148F-FPOE v7.0.4 build0071.
Solution	Issue: PoE power fault errors occur on FortiSwitch-148F-FPOE v7.0.4 build0071 using PoE Firmware Version 2.2.3. User-Impact:  PoE-powered devices (PDs) such as IP Phones or Access Points connecting to FortiSwitch-PoE ports do not power on. Summary: FortiSwitch shows the following PoE power fault errors in the below command outputs: get switch poe inline diagnose switch poe status <Port_ID> Power Fault: Error Type 38 (Port is off: Discharged load) Power Fault: Error Type 36 (Port is off: Voltage injection into the port) Cause:  When the FortiSwitch-PoE port is connected to a PSE (Power Sourcing Equipment) such as a 3rd party PoE FortiSwitch, the 3rd party PoE FortiSwitch may inject power into the FortiSwitch port. This causes the PoE errors 'Discharged load' and 'Voltage injection into the port', which may harm the device. Fix:  Run the cable diagnostic command on all ports, one by one, to detect if a port is in a 'short' state, and solve this state before following further steps: diagnose switch physical-ports cable-diag <port_name> Disable 'poe-pre-standard-detection' if it's not in use: The purpose of 'poe-pre-standard-detection' (also called legacy detection or capacitor detection) is to support old PDs like the Cisco 794x phone released decades ago. If the user doesn't have these old PDs, pre-standard detection should be kept disabled by default. There was a bug in v7.0.3 GA where 'poe-pre-standard-detection' is always enabled. The issue is fixed in v7.0.4 GA. With v7.0.4, 'poe-pre-standard-detection' is disabled by default. FortiGate CLI (for Managed FortiSwitches): config switch-controller managed-switch     edit <FortiSwitch_serial_number>         set poe-pre-standard-detection disable     next end FortiSwitch CLI (For Standalone FortiSwitches): config switch global     show full         set poe-pre-standard-detect disable end Disable PoE status on the 3rd party PoE Switch or FortiSwitch that's plugged/connected into the FortiSwitch port: FortiGate CLI (For Managed FortiSwitch units): config switch-controller managed-switch     edit <FortiSwitch_serial_number>         config ports             edit <port_name>                 set poe-status disable         end end FortiSwitch CLI (For Standalone FortiSwitch units): config switch physical-port     edit <port         set poe-status disable end Refer to this KB article to disable POE on Managed FortiSwitches inter-switch links: Technical Tip: How to Disable PoE on FortiLink Ports. Power-cycle the affected FortiSwitch using the below command if the PoE error does not go away: execute reboot Note: To avoid loss of configuration settings, download a backup of the FortiSwitch configuration before attempting a reboot. See Page 77 of FortiSwitch 6.4.5 - Managed by FortiOS 6.4 for more information: If error 36 and error 38 are gone after reboot, the issue is fixed. If error 36 and error 38 are still present, log a ticket with Fortinet Support with the affected FortiSwitch Serial Number. If this PoE error is occurring between two adjacent/interconnected FortiSwitches, attach the following outputs from both FortiSwitches to the ticket for further analysis: get hardware status get switch poe inline diagnose switch poe status <Port_ID> show full-configuration switch interface show full-configuration system interface show full diag debug report Related article: Troubleshooting Tip: Diagnosing a PoE fault on a FortiSwitch.