The 4a63 fault code is unique to BMW vehicles.
What are the symptoms of this fault?
The car will turn over but not start.
When does the fault occur?
It usually occurs when trying to start the vehicle with a dead battery, but there have been reports of it happening whilst changing the drive battery too.
What does the fault mean?
The vehicle’s ECU and Immobiliser system have ‘lost synchronisation’. In other words the main engine computer is no longer getting the message it needs from the immobilser to start the vehicle.
People have been talking about DME, EWS and CAS. What are they talking about!?
BMW have helpfully named the parts in their cars differently from all other manufacturers, here’s a quick guide:
DME (Digital Motor Electronics) – This is the name for the vehicle’s Engine Control Unit or ECU. It controls all major aspects of your engine and receives reports from all other computerised units in the vehicle.
EWS (Electronic Drive-Away Protection) – This is the vehicle’s immobiliser and stops people driving your vehicle with an unprogrammed key. Late BMW’s, that use a slot key, now have a different immobiliser system called ‘CAS’ – the 4a63 fault code will usually still mention ‘EWS’ on these vehicles though.
CAS (Car Access System) – This is an updated immobilser and anti-theft system. It’s only found on vehicles that use the newer ‘slot-in-the-dash’ keys.
How do I fix the problem?
BMW diagnostics are needed to reset the values in both the DME and the EWS or CAS, this will resync the two units so they can talk to each other again.
Does my car need to go to the main dealers?
No. Autolox are on hand to fix this problem! We have the necessary diagnostics and knowledge to get your BMW back on the road again. We have already helped lots of customers in this exact same situation.
How much does it cost?
We charge a flat rate of £120 for this service. No hidden costs. Please feel free to give us a ring!