Well, sorry, I probably switched from one problem to another very fast.
The squealing noise problem was never related to the lambda sensor. It was something that was bothering me and I just want to get it fixed I checked the belt at the garage today and I been told that it's fine. It's something else that is making that noise. But that will have to be investigated.
Reason why I wrote about the lambda sensor was because engine management light came on on my dashboard.
After I ran a ford focus error reporting function (holding down that button on dashboard and starting the engine) it gave me an error DTC 9318 which is related to a low voltage.
Today I did test my battery in a garage and it's fine. Charging system is also fine.
Then they connected it to the computer and actually scanned the system. It said the cause of the Engine management light is the lambda sensor. (Well, I really hope it is as it said that the problem is in the catalytic. So my friend just recommended me to change the sensor.)
But anyway, it's kind of weird that when you read the error via build in error reporting system it say that it's an DTC 9318 error while when you connect it to the computer it say that it's a error in catalytic.
Hope this makes any sense
Anyway, I will try and change the sensor and see will it help. It's only an 10 minute job there.
Will keep you updated on how things are going with the car