You plug in the ENET cable, open E-Sys, click Connect, and nothing happens. Connection via VIN stays greyed out, the target list is empty, or E-Sys tells you there's no ZGW. The ZGW is the car's central gateway, the module E-Sys talks to first. If E-Sys can't reach it, it can't reach anything.
Nearly every case comes down to the same few things, and a two-minute test tells you where to look.
Based on the F30post threads Unable to connect via VIN !! and ZGW finds nothing. Can't connect.
The Five Things E-Sys Needs
This is shawnsheridan's checklist, posted in the first thread for everyone stuck at this point:
- PSdZData installed properly. The Target list in the connection window shows several chassis entries, not an empty box.
- A good ENET cable that makes solid contact in the OBD port.
- Proper voltage. The engine running, or the car on a charger.
- No firewall or antivirus running on the laptop.
- A fallback IP address of 169.254.x.x on the laptop's network adapter. The adapter has to get its address automatically (DHCP), never from a static IP.
The Two-Minute Test
A small tool called ZGW_SEARCH.exe looks for the car's gateway on the network. Run it with the cable in and the ignition on. atzebmw's way of reading it:
- It shows the car's IP address and VIN. The cable, the car and the laptop's network are fine. The problem is in E-Sys or PSdZData.
- It shows nothing. The problem is the laptop, the cable or the car.
If the tool won't even start, ktula had to register mswinsck.dll as administrator before it ran.
ZGW_SEARCH Finds the Car
The Target list is empty. E-Sys can see the car but has no data to talk to it with. ktula's SWE folder turned out to be empty. PSdZData belongs in C:\Data\psdzdata, E-Sys's data path has to point to C:\Data, and every chassis folder needs an empty dist folder. Our guide to updating PSdZData walks through all three.
The dealer just updated the car. Frogman remembered shawnsheridan saying that very old PSdZData can stop E-Sys connecting. If the car has been programmed recently, newer PSdZData and a matching E-Sys are the next thing to try.
ZGW_SEARCH Finds Nothing
The laptop
- Wait for the address. Frogman's tip: don't click Connect until Windows has given the adapter its 169.254.x.x address. Run ipconfig in a terminal to check. Connect before that and E-Sys never finds the car.
- No static IP. If the adapter ever had a fixed address, the car won't answer it, bcornwellatl warned. Set IPv4 to obtain an address automatically. Just unplugged from your home network? Restart the laptop, or disable and re-enable the adapter, before you plug into the car.
- Firewall, antivirus and other adapters off. NOGRP also switched off Wi-Fi and Bluetooth while testing.
- Reset Winsock. shawnsheridan's last resort on the laptop side: run netsh winsock reset in an administrator terminal, then restart.
- Virtual machines need a bridged network. steddyman and drhousedk both ran E-Sys in a VM with the network bridged. It works, but it's one more layer between E-Sys and the car. Here's what a coding laptop needs to run Windows directly.
To rule the laptop out completely, plug its Ethernet port into a router. If the router can't see it either, the laptop's port is the problem (Almaretto's advice).
The cable and the port
- Cheap cables fail. drhousedk's connection worked once and never again. A borrowed cable worked every single time.
- Check how the plug sits. Several owners describe plugs that are loose or hard to seat. pikcachu found the legs of pin 12 in one car's OBD port bent back, so the cable never made contact.
The car
- Let it sleep. This came up more than anything else. Unplug the cable, switch everything off, lock the car and leave it for about 15 minutes so every module shuts down. Frogman, HFW003 and pikcachu all fixed it this way. Connecting and disconnecting several times in a row seems to make it worse.
- Charge the battery. capt_slow's car refused to connect with a low battery, even with the engine running. A few hours on a charger sorted it.
- After a dealer visit. One owner's car didn't answer on ENET at all until the dealer's next software update fixed it (uadissa).
Connected, but Reads Time Out
If E-Sys connects but Read Coding Data times out on most modules, start the engine. That was HFW003's advice to steddyman, and every read worked straight after. Coding with the engine running, or on a strong charger, also protects you from a write that dies halfway, like the one in our F30 coding list.
FAQ
Is there another way to connect besides Connection via VIN?
E-Sys can also connect through the gateway URL, and our flashing guide uses that to flash the ZGW itself. But if Connection via VIN can't find the car, the gateway URL won't reach it either. drhousedk tried the car's address on port 6801 directly and got nothing. If a second laptop fails in the same way, shawnsheridan's verdict is that it's the cable or the car's gateway.
Will a newer E-Sys fix it?
Only when the cause is old PSdZData after a dealer update. A cable, voltage or network fault looks exactly the same in every E-Sys version.
The attached one-page PDF has the checklist and the test in order. Been through all of it? We can take a look in a remote session.
Credits 
This comes from four F30post threads: Unable to connect via VIN !!, started by 10nelyboi in 2014, ZGW finds nothing. Can't connect, started by steddyman in 2014, No ZGW found - been connected once by drhousedk, and HELP: E-Sys newbie problem by ktula. The checklist is shawnsheridan's. Thanks also to Frogman, bcornwellatl, capt_slow, pikcachu, atzebmw, HFW003, Almaretto, uadissa and everyone who came back to say what finally worked.