The most common cause of the FBS4 ESL getting blocked is due to battery voltage on the vehicle. Mainly when the Key has been left inside the EZS for some period of time, ( over night, or some days )
The scenario is, as the battery voltage drops on the vehicle while the Key is still inside the EZS there will be multiple authentication attempts between Key / EZS and ESL. Each time there is a failed authorization between the EZS and the ESL the error counter blocks inside the ESL will increment. If this continues, the result will be a Blocked ESL.
As you can see from this detailed explanation, the majority of these Blocked ESL are not due to mechanical / hardware related problems .. Rather they are the result of error accumulation related to voltage problems.
