MHD hardware
MHD flashes your BMW through the OBD port. To do that you need a compatible MHD adapter or OBD cable and a licence for your car. Here is exactly what the hardware does, what is compatible, and the answer to whether it works with xHP.
What it is
MHD is a flash tune, the calibration is written onto the car through the OBD port. There is no piggyback box wired into the engine bay, so the only hardware between you and the car is the adapter, sometimes called the MHD box, MHD flash adapter or simply the OBD cable.
You connect, MHD reads the ECU, then writes the map. The adapter is the link that makes that possible, nothing more complicated than that.
What you need to flash MHD
A compatible vehicle
A supported BMW engine and model, for example N54, N55, S55, B48, B58, S58 or N20.
An MHD licence for that car
The licence unlocks the maps for your specific vehicle. Adapter and licence are separate purchases.
An MHD adapter or OBD cable
A compatible OBD interface that gives MHD a stable, reliable link to flash and data log.
A phone or laptop
The MHD app to read the car, choose your map, flash and log.
Not sure which engine code you have, or whether your year is supported? Send us your reg and we will confirm before you buy anything. See MHD by engine and model.
Compatibility
The adapter is the connection. What matters for compatibility is your chassis, your engine and the licence. Here is how it breaks down.
Engines
MHD covers a wide spread of turbocharged BMW engines. The popular codes include the ones below, with exact model and year support confirmed on enquiry.
The connection
Three things work together, the adapter links you to the car, the app does the flashing, and the licence unlocks the maps for your vehicle. Get all three matched to your spec and you are ready.
A word on cheap dongles, generic OBD adapters are tempting on price, but an unstable connection part way through a flash is the most common avoidable cause of a failed write. For a flash tune, connection stability matters more than saving a few pounds. If you are unsure what is compatible with your exact car, ask us first. For how the licence works, see MHD licence.
MHD vs xHP
This is the question we get most often, so here it is plainly. MHD and xHP are two different platforms doing two different jobs, and they each use their own hardware.
The short answer, the MHD adapter is for flashing the engine ECU through MHD. It is not a tool for flashing xHP transmission maps. They are not interchangeable.
What MHD does
Flashes the engine ECU, the DME
Your power and torque maps, boost, fuelling and timing, written over OBD with the MHD adapter.
Uses the MHD app and adapter
The adapter is matched to talking to the engine ECU through MHD, on your phone or laptop.
What xHP does
Flashes the gearbox controller, the TCU
Shift firmness, shift speed and behaviour on supported automatic and DCT transmissions.
Uses its own xHP Flasher tool
A separate platform with its own connection. Buying an MHD adapter does not unlock or enable xHP.
Want both, an engine tune through MHD and a gearbox tune through xHP? That is a very common pairing, they are just done with their own tools. Tell us your model and we will set out exactly what each one needs so they work together cleanly. See MHD Stage 1 and Stage 2.
Buy or enquire
The fastest way to avoid buying the wrong thing is to tell us the car. We will confirm the adapter, the licence and the tune for your exact engine and model, in plain English, before you spend anything.
How it works
Send your reg and engine
Message us on WhatsApp or through the contact page with your car details.
We confirm the hardware
We tell you the compatible adapter or OBD cable, and whether you need anything else.
Licence and tune sorted together
We line up the MHD licence and the map for your spec so it all matches up.
Flash with support behind you
If you get stuck connecting or flashing, we will talk you through it.
Keep reading
The adapter is one piece of the picture. These pages cover the licence, the stages, and how bootmod3 compares if you are weighing up platforms.
Comparing platforms or pulling the full kit together? See bootmod3 Stage 1 and Stage 2, bootmod3 licence and bootmod3 by model. Adapters and a few other bits live in the shop.
Common questions
No. MHD and xHP are two separate platforms that do different jobs. MHD flashes the engine ECU (the DME), while xHP flashes the gearbox controller (the TCU) on supported automatic and DCT boxes. xHP uses its own flashing tool, the xHP Flasher, with its own connection. The MHD adapter is built for talking to the engine ECU through MHD and is not a tool for writing xHP transmission maps.
The two are not interchangeable. xHP has its own supported cable and app for transmission flashing, so you should follow xHP guidance for the hardware it needs rather than assuming your MHD adapter covers it. Plenty of owners run both an engine tune through MHD and a gearbox tune through xHP, they are just done with their own respective tools. If you want both on your car, tell us your model and we will set out exactly what each one needs.
Treat them as separate purchases for separate jobs. The MHD adapter and licence get the engine ECU flashed through MHD. A gearbox tune through xHP is bought and flashed on its own platform with its own connection. Buying an MHD adapter does not unlock or enable xHP, and vice versa. We can supply and guide both so the engine and gearbox sides work together cleanly.
MHD writes the map to your BMW through the OBD port, so you need a compatible OBD adapter or cable that gives MHD a stable link to the car. The exact item depends on your chassis and how you prefer to connect, wired from a laptop or via a supported OBD interface. We do not recommend the cheapest generic dongle, because an unstable connection mid-flash is the most common avoidable cause of a failed write. Send us your reg and we will confirm the right hardware before you buy.
No. A JB4 is a piggyback module that wires into the engine bay and intercepts sensor signals, it is a physical box that stays fitted to the car. The MHD adapter is just the connection between your phone or laptop and the OBD port so MHD can flash the ECU directly. MHD is a flash tune, not a piggyback, so once the file is written the only hardware involved was the adapter used to write it.
Not sure what you need?
Send your reg and engine and we will confirm the right MHD adapter, the licence and the tune for your exact spec, no guesswork.
