Evening ladies and gents,
Called to an all keys lost situation on a 2011 E90.
On opening the car the alarm was giving it some however, since downgrading the CAS firmware and adding two new keys in the car no longer deadlocks and the alarm no longer sets. There are no relevant DTCs and I've tried a battery reset. Bizarrely on refitting the battery the red alarm light lit up nicely however as it should but the alarm wouldn't sound on the door being opened with the key and then the interior alarm light wouldn't come on at all after that.

Would it help reinstating the original CAS Firmware?
Or any other thoughts please?

Many thanks
Ian

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Always restore CAS firmware after doing such operations...Different I-level software in various control units may result in unexpected behaviour.

Thankyou Roxetteer...I shall try this tomorrow and report my findings

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For all key lost you no need downgrade CAS only read ISN from DDE, after programming first key can you program another one, watch here:

So CAS Firmware has successfully been updated but alas still no joy in trying to reactivate the alarm. If I go into the DWAI via Diagnose it tells me the alarm is disarmed. I've tried almost every different combination of enabling and disabling sirens/sensors but still no joy

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OK I should ask...genuine alarm or aftermarket? Give me VIN please.