Key fob stopped working after BSI reset

[aerodynamica]

Been working on the alternator pulley and so disconnected the battery taking all the normal precautions. When reconnected, I performed the bsi reset including the pairing of the key fob. However when I get to the step where you turn off, remove key via open window and open/close remote locks nothing now happens. It was fine before.

No doors or anything opened before the procedure However I did mistakenly forget the step of turning on the sidelights first. Is that the cause?

I repeatedly tried to re-pair the key fob will all the steps and still nothing.

Any thoughts?

[Paul-R]

Which vehicle is this?
How old is the battery?

[aerodynamica]

C5 x7 2.0 hdi and brand new car battery.


Having said that, I didn't think the remote battery might have gone because it worked before the work. I'll change it first and see if that helps

[Paul-R]

When I said battery I meant the main car battery, not the battery in the remote. Is the answer still the same?

[wheeler]

I did mistakenly forget the step of turning on the sidelights first. Is that the cause?

No, the ‘sidelights’ bit is not something i have ever done when reconnecting a BSI equipped vehicle battery & have never had any issues like that, i have done this literally hundreds of times like this.

[aerodynamica]

Yes the car battery is new one month ago and has a higher CCW than the outgoing battery.

[aerodynamica]

I did mistakenly forget the step of turning on the sidelights first. Is that the cause?

No, the ‘sidelights’ bit is not something i have ever done when reconnecting a BSI equipped vehicle battery & have never had any issues like that, i have done this literally hundreds of times like this.

Ah OK, I thought this sidelights bit was the done thing. Just coincidence this went wrong the one time I miss it out.

Just went to get a new remote battery cr1620 and some hard to find. Never see it in the sainsburys near me. Plenty CR2016 mind..

[aerodynamica]

Ok, I did have a stock of CR1620s in my digital watch collection service kit, o yes, I collect vintage digitals... anyway, I replaced the battery in the keyfob and no difference. I performed the full BSI reset once more and re-paired the keyfob again and still no response.

I located my old keyfob that I don't use because it has a fault with the immobiliser however, the remote on it was still working and indeed, when I tried it there it operates the locks as expected so there must be something wrong with the current keyfob. New keyfob battery and no function.

It is an aftermarket item I had to get from a locksmith and he had to send off for the keyfob.

[PaulC5]

Try unlocking with the working fob and then locking with the other one. Try this a few times and see if it gets it to work. Our C5 spare fob loses initialisation if not used and I have gone through the correct initialisation procedure to sort it (as in the handbook for fob battery replacement) but have found just doing the unlocking/locking thing gets it working. It could do with a new battery though which might fix it properly. I have found that old batteries than still show 3 volts do not work well but a new one that also shows 3 volts works.

[aerodynamica]

Try unlocking with the working fob and then locking with the other one. Try this a few times and see if it gets it to work. Our C5 spare fob loses initialisation if not used and I have gone through the correct initialisation procedure to sort it (as in the handbook for fob battery replacement) but have found just doing the unlocking/locking thing gets it working. It could do with a new battery though which might fix it properly. I have found that old batteries than still show 3 volts do not work well but a new one that also shows 3 volts works.

I actually tried this earlier after I found the old fob worked. But it didn't do anything. Just seems strange the new current fob (that is only 4 months old) would stop working at the bsi reset. Could be coincidence but I feel something else is at play here.

Oh, I swapped batteries between the fobs and still only the old one works as remote.

[aerodynamica]

Question: is it necessary to re-pair the remote when you reset the bsi ?

Is it possible to re-pair the remote without the bsi reset?

[GiveMeABreak]

Yes it is, just follow the reinitialisation part of the BSI Reset / Battery Disconnect / Reconnect Procedure for the fob.

Sometimes you need to wait a while longer after battery reconnection. Just try locking and unlocking the car with the fob a few times. Then insert the key in the ignition to accessories only and press the lock button for a few seconds, release and remove the key. Repeat the locking unlocking with the fob, then try starting the vehicle again. But of course make sure you have a good working battery in the fob first.

[wheeler]

Do you have a picture of the aftermarket fob you have? does the new fob still start the car?

If the other remote is operating the locking ok it looks like an issue with your new fob, you may need to to a full key reprogramming with Diagbox & the 4 digit code.

[aerodynamica]

Do you have a picture of the aftermarket fob you have? does the new fob still start the car?

If the other remote is operating the locking ok it looks like an issue with your new fob, you may need to to a full key reprogramming with Diagbox & the 4 digit code.

The new fob does start the car just the remote lock aspect that's stopped. The old fob unlocks the doors ok but often can't start the car and a warning comes up saying "electronic anti theft fault" so I assume something on the old keyfob has thrown in the towel.

[GiveMeABreak]

Some aftermarket fobs don't have the required circuit / electronics to operate the remote elements like the third button function or the locking. These have to be compatible for these functions to work as I’m guessing you're finding out .