Faulty Lamda - MK4 Golf

[milly143]

Last week my car was loosing power while I was driving and shortly afterwards the exhaust emmissions (sp) warning light came on. I took it straight to VW who checked it out and said it was something to do with a faulty temperature guage or something. They said they fixed it but 10 minutes later the light came back on. I took it straight back to VW and after checking again, the mechanic explained to me something like the engine had been reading the temperature wrong and the lamda had got used to the emmisions coming through the exhaust (which were bad) but now the temp thing had been replaced it didn't recognise what was going through the exhaust now (the right emmissions) and that the lamda would need replacing. I got the impression that he was just givng me any old excuse as it didn't make sense that the light came on in the first place before they had even touched it. Does anyone have any ideas about what might really be the problem? Sorry if that doesn't make much sense.

[woodchopper]

The mechanic makes sense.

[milly143]

Phew! Thank you!