Are you sure you typed the correct DTC "P" code? You can simply google "BMW OBD II P1434" to find more info about that code.
You can clear an OBD II code...but if the issue still exists...the sensor will continue to register the fault...so yes, it will come back if the problem is still there.
The SES/CEL/MIL light illuminates when a sensor registers a fault twice....that's the way the OBD II system was designed (see the 2nd paragraph in the 3rd bullet in information below):