What are the reasons why a BMW cannot start when locked?
3 Answers
The specific details are as follows: 1. ELV: The ELV can only interlock when the vehicle is stationary and the engine is off. After the unlock and lock processes are not executed, the ELV device is in a power-off and locked state. 2. CAS: The CAS is the main unit of the convenient access and start system, primarily responsible for receiving the key signal from the antenna and verifying the legality of the key. If the key is valid, the LIN bus sends an unlock signal to the ELV. The ELV is the control unit for the electric steering lock. Upon receiving the signal from the CAS, it sends an activation signal to the steering column motor, controlling forward and reverse rotation to manage unlocking and locking. 3. Issues with ELV-equipped vehicles where the steering wheel lock cannot be unlocked: The key battery is dead, preventing signal transmission; the car battery is dead or there is an antenna issue, causing the CAS to fail to receive the key signal and unable to verify; LIN bus failure, preventing signal transmission to the ELV; ELV control unit damage; steering column motor damage or faults in the wiring from the motor to the CAS; CAS malfunction.
As a long-time BMW owner, I've encountered this non-starting lockout situation quite often. It's usually caused by a depleted key fob battery or the anti-theft system being accidentally triggered. BMW's anti-theft features are highly sensitive - if the key battery is low or there's electromagnetic interference in parking lots, it will lock the engine to prevent theft. A dead car battery is another major culprit, failing to provide the necessary power for starting, or a faulty starter motor causing ignition failure. Electronic system glitches like ECU malfunctions can also disrupt signals, making the car think it's being stolen. Regular checks on your key fob and car battery condition are essential, and avoid leaving the car unused for too long to prevent battery drain. At the first sign of starting issues, try replacing the key fob battery immediately. If that doesn't work, use the mechanical key for manual unlocking, but don't force it to avoid damaging door locks. For safety, it's best to promptly seek professional help from a technician who can use diagnostic tools to check error codes.
As a BMW owner, I've encountered the ignition lock issue a few times, mainly due to key fob or car battery problems. The key fob battery weakens over time, especially smart keys that require frequent button presses drain faster; spare keys may not be recognized if never activated. The car battery typically lasts 3-5 years - aging batteries with insufficient voltage can cause complete electronic lockout. Simple checks: first press the unlock button to see if there's any response (no sound indicates key issues); open the hood to measure battery voltage (needs charging if below 12V); listen for clicking sounds during startup (audible clicks without engine turnover may mean starter failure). Additional tips: batteries deplete faster in cold winters, so regularly start the car to avoid prolonged inactivity. If DIY solutions fail, immediately contact a 4S shop to prevent minor issues from escalating.
