Home/Installation/Soft handover
Soft engine handover on cars with a Start/Stop button
Soft handover means that after a remote start you disarm the car, get in, and the engine keeps running. Without it, on cars with a Start/Stop button the engine cuts out the moment you open the door. I do this by changing the system logic, without hiding the factory key in the cabin.
What happens without soft handover
The system starts the engine while the car is still armed. The moment you disarm it and open the door, the factory authorisation system cannot find a key near the steering column and shuts the engine down. You then have to start it again — and the warm-up you paid for loses half its point, because in a hard frost the cabin cools down while you restart.
The standard fix most installers use is an immobiliser bypass: a second factory key, or its chip, is hidden inside the cabin so the car always “sees” a key.
How I do it
I do not hide a key. The soft handover is built on the logic of the StarLine unit itself: authorisation is passed at the moment you are already inside, so the engine never gets a chance to stall. Your factory key stays in your pocket.
It takes longer — the logic is written for the specific car rather than picked from a template. That is why a custom install takes 5 to 12 hours, 8 on average while a basic one takes 2 to 4 hours. The difference is exactly the writing and debugging of that logic.
Why the bypass matters
- A key inside the car is a ready-made theft kit: break into the cabin, get factory authorisation, and tags and immobilising circuits no longer help.
- You lose the use of your second key. It either sits at home “just in case” or has to be ordered from the dealer, and programming a new key costs real money on many cars.
- When you sell the car you have to remember to take the key out — otherwise it leaves with the car.
The dealer warranty, honestly
This deserves a straight answer rather than a breezy “we don’t cut anything”. Remote start and alarm functions really do connect over CAN/LIN and through factory connectors — there is nothing to cut there. But a soft handover without a hidden key always means cutting into a factory circuit — there is no other way to build it. On some cars a diode is added on top, and that is spliced in as well. I tell you that before the work starts, not once the car is already apart.
There is one exception: cars with a conventional ignition lock that are being retrofitted with a Push Start button. There the soft handover is part of the system from the outset — no cutting into a factory circuit, and it is the only way to get it without touching the factory wiring.
It is a deliberate trade-off: an intervention in the wiring in exchange for your second key not sitting in the cabin, ready to leave with the car. The choice is yours — my job is to explain exactly what will be done before I pick up a tool.
The second thing worth knowing: a dealer can raise a claim about any aftermarket equipment, even when the fault has nothing to do with it. That is a conversation at the service desk more than a technical matter. What I do about it: joints are soldered and insulated, I explain what was done and why, and I leave the install in a state where it can be put back to original.
What else I do
FAQ
Will the engine really not stall when I get in?
No. We check it together on the spot: disarm, you get in, you pull away — the engine keeps running the whole time.
What if I get in ten minutes later?
The engine runs for as long as the warm-up settings say. If you get in within that window, it stays running. If the warm-up is already over, the car shuts down normally, as it should.
Can this be done on any car?
On cars with a Start/Stop button and factory keyless authorisation. Send the model, year and trim and I will tell you about your car before any work starts.
Will the dealer warranty hold?
An honest answer: it depends on what we do. Remote start, alarm functions and a Push Start retrofit connect over CAN/LIN and through factory connectors — nothing needs cutting there, it is all built on flexible logic. But a soft handover on a car that came with a Start/Stop button from the factory always means cutting into a factory circuit; there is no other way to build it, and on some cars a diode is added on top, spliced in as well. The exception is a key-ignition car being retrofitted with Push Start: there the soft handover is already part of the system and nothing has to be cut. I tell you this before the work starts, and joints are soldered and insulated. And separately: a dealer can raise a claim about any aftermarket equipment, even when the fault has nothing to do with it.
Can you add soft handover to a system that is already installed?
If I installed it — yes. If someone else did — only a full reinstall: in another person’s wiring there is no way to see what was cut and where, so I cannot stand behind the result.
What does it cost?
The price depends on the car and the set of functions. Send the model, year and trim — I quote an exact figure before the work starts, with no surprises later.
Let’s talk about your car
Send the make, model and year — I’ll tell you which functions can be wired on it, how long it takes and what it costs.