Hey guys,
The gearbox eas working perfectly fine before I change the head gasket. Now when I put it into drive it stays in first until I let go of the Throttle, then it goes into neutral. But when I put it into eco mode it shifts perfectly fine but it won’t go into 4th just stays in 3rd. I changed the Inhibitor Switch, did a full gearbox service and check all the fuses
I don’t know what else to do and wondering if I need to get a new gearbox or it’s a electrical problem
Thanks

Hello, the TCM controls shifting. If there's an issue with the module, it could lead to improper shifting. Consider resetting or reprogramming it if necessary.