jay

there usually located on the rear of the engine on bmw, I know in the UK if its accessible without the engine being taken out it is about £700 on average for most cars and around £1,000 or anything that has to have the engine removed (so usually another 3rd of the cost more anywhere), the chain tensioners are renowned for failing in a lot of bmw’s though, have you check that first? and depending on the mileage if the engine does have to come out then maybe a clutch will be required too.

most normally come with either double sided sticky tape or two pins off the back of the emblem that pop into the panel. from the factory for the rear emblem it may have both

loose wiring, broken wire or water in electrics most probably, does the cluster and lights stop working whilst your driving? have you checked the battery terminals are secured tightly and there’s no dirt or discharge on them?

off the brief description i’d take a guess that timing is slightly out, take it to a garage to get it checked and they’ll let you know if it is.

you won’t need to check for sensors, the A/C system doesn’t have any that will directly throw up a code just for that, if the sensor was faulty on the ASC then the light would be on the dash constantly and its would constantly be disengaged, have you noticed if the ABS or traction is faulty or are they still working okay? a garage may be able to get to the bottom of it a lot quicker

part aren’t correctly matched probably, if it was a wiring issue then it wouldn’t start at all and if the immobiliser was faulty then it wouldn’t start either at all, although its usually engine related issues some cars take time to recognise a fault via sensors and other bits and bobs, usually across two starts and compare the readings then throw up an error, maybe that at a long shot but I would just get a garage or the locksmith to test all the parts that have been fitted to make sure they are all in working order and fitted correctly first, immobilizers can be very delicate things and can mess up an ECU easily if one little thing is missed.

You need to erase it from the ECU, depending o the other car you paired it with, some you can do by re-programming the key you want for that car and just don’t use the key you want to use only on the one car, on some cars that will remove any currently programmed remotes and only recognise the one you’ve just done, on some others you may need a car key technician to come and delete it via a computer, what is the other car you paired it with, is it the same Toyota?

as long as it isn’t the I4 engine in which case it will only have one bank then follow the headers from the engine towards the exhaust and they shouldn’t be much further away than an arms length screwed into the exhaust, usually one before a cat and one after, they are very delicate so be careful not to man handle them too much on the sensor end.

any change the sensors were fine to begin with and the timing is off?

the button on the board to lock it has probably broken, you can get a new one soldered on by most people that do key repairs.