Something that I've not mentioned on here, which I keep meaning to and then forgetting is that I've previously mentioned the eml coming on and giving a code for the rear lambda sensor causing an issue.
I've checked the emissions data sheet from the last MOT and it's fine. Bearing in mind that the eml started coming on soon after I bought it and I checked it for codes soon after I got it home and it had none, it was a bit weird.
Now I've had this before on the Mrs old E46 325i and had the lambda sensors tested and swapped about but that gave the same code for the same lambda sensor, despite another one being there. My mechanic was an recently ex BMW technician with BMW diagnostic kit and he knows his onions. He said that the catalytic converters on those never fail, so refused to change it. Sure enough, the emissions were fine too. The solution was to stop using Tesco petrol.
Then I had exactly the same issue with my Suzuki Jimny but had already started to use other petrol, so that was solved too.
I was therefore suspicious of the Jet petrol from the petrol station up the road to us, which is as cheap as Tesco.
Given I've come from a 2.2L BMW E46 320i auto, to a massively modified Suzuki Jimny (really uneconomical) to a 1L Micra, my fuel costs are much lower. As such, I can afford to put in BP from an expensive petrol station on my way home after late shifts once a fortnight. My fuel bill has still halved!
Guess what! I've not had an eml or even any codes since I've run a couple of tanks of BP through it!
Kirkynut