| ECU LED | Meaning | Action |
| Cloud LED — on | Connected to EMA server | Normal operation |
| Cloud LED — off | No server connection | Check internet / firewall |
| Wi-Fi LED — blinking | Searching for network | Reconfigure Wi-Fi in ECU App |
| All LEDs off | No power | Check power supply / outlet |
1. Restart the ECU
Power off the ECU, wait 1 minute, then power it back on. Allow 5 minutes for it to reboot and
reconnect to your router and the EMA server. Check the cloud LED after restart — it should turn
solid on once connected.
2. Check Wi-Fi antenna and connection
Confirm the Wi-Fi antenna is fully screwed in and positioned outside any metal enclosure. Use the
ECU App to verify the Wi-Fi connection is active. If your router password or SSID has changed, you
will need to reconfigure the ECU's Wi-Fi settings through the ECU App.
3. Try switching between Wi-Fi and Ethernet
If Wi-Fi is unstable, connect the ECU directly to your router using an Ethernet cable. If Ethernet
fails, switch to Wi-Fi. When using Ethernet, confirm the cable is undamaged and the router port is
active.
4. Check for firewall or router restrictions
The ECU requires outbound TCP access to APsystems servers (ecu.apsystemsema.com,
ecuna.apsema.com, ecueu.apsema.com) on ports 8995-8998, 9001-9004, 9220, 9222, and
9227-9228. If your router has MAC address filtering, whitelist the ECU's MAC address.
5. AP Systems ECU to WiFi Network Video Guide - Video Guide