Mercedes Immobiliser Systems and Steering Lock Problems

Mercedes have always been at the forefront of vehicle security. They were one of the first manufacturers to introduce 4 track laser key ignition locks and these remain to this day one of the most secure and difficult to pick types of lock.

However, with complexity comes risk of mechanical failure, and Mercedes definitely embraced a “fail secure” concept – where other makers' locks might become easier to open with age, Mercedes ignitions tend to fail very much in the LOCKED position. This makes it harder for a thief to pick the lock, or open it with another key but it can make your life very difficult when you insert the key and your ignition barrel refuses to budge! Disaster. The temptation is to force it – but this can be a terrible mistake, with the keys designed to fracture near the handle and components in the lock designed to break compounding this problem.

Starting in the 1990's they shifted the focus of their vehicle security to electronic immobilisation systems or “DAS” (drive authorisation system) as did most other manufacturers in Europe. In fact by 1994/5 it was a requirement for vehicles sold in the UK to have a factory fitted “Thatcham approved” immobiliser. This was the start of car keys as we know them today. The earlier systems were deactivated with a button on the key.. but as anyone who drove back then can tell you, this was a flawed concept. If the key battery went flat then you were stuck. Not to mention the synchronisation issues if the button was pressed when you were out of range, the car battery was low, or there was radio interference in the area..

In 1998 Mercedes brought out their DAS 3 system which is the iconic fish shaped key Mercedes owners all over the world know today. This features a remote control which opens the doors and turns off your alarm. This is done from a distance by radio. The engine start is authorised when the key is put in the ignition reader slot – by infra red communication. The reader powers up the the key inductively when it is placed in the slot, meaning even if your key battery is flat, you can still open the car with the emergency key and start it up.

Modern Mercedes keys are very durable and have a long battery life but even the best designed systems can develop problems.

• Low battery situations and hardware failure in the onboard chips can lead to non-start. We can replace your key.
• Steering lock failure happens eventually and will prevent the vehicle from starting. The steering lock can jam in the locked or unlocked position. If it is on the way out then it may sound slow or require a few attempts to unlock. We can sort this out for you.
• The key reader itself (“EIS” or “EZS”) can become faulty. Symptoms include – no crank - crank, but no start – car starts, but dash lights don't work – steering won't unlock. We can program a replacement unit for you