Hi,

I have just replaced my engine in my Corsa C 04-plate, engine code Z12XE. The mechanic that did it is very knowledgable and reliable. The car runs spot on, however the mechanic can for the life of him figure out why the emissions light/engine management light stays on. He connected it to a diagnostic machine and it kicks out an Undefined ("U") error code.

Does anyone know what this code means, where do I start to look to try and fix this problem?

Also the airbag light comes on when the engine is off and the key is out the ignition however, it goes off when the car is running. What could cause this?

Another issue I have is that the handbrake light stays on when the handbrake is down even though the brake fluid is full and the handbrake cables have been replaced. A tap on the dashboard (above the light) turns it off until car is started up again however, the light doesnt always come on. What could cause this?

I know this is lengthy but thought I would be thorough as this is definetly baffling my head.

Thanks in advance