MaxxECU Expansion Module: More Inputs and Outputs Without Buying a Bigger ECU

Quick answer: The MaxxECU Expansion Module is a CAN-based I/O expander that adds 12 analog inputs, 4 pulse inputs, 4 × 12 V sourcing outputs at 5 A and 4 H-bridge outputs at up to 15 A to any MaxxECU — from the smallest MINI to the flagship GEN2 RACE. It lives in an IP68 black powder-coated aluminium case with a Superseal 1.0 connector, weighs 195 g and draws 45 mA. Critically, it appears directly inside MTune with no manual CAN message configuration — the inputs and outputs simply become available like any other channel. GEN2 ECUs support up to four modules with the pre-defined configuration at a 0.5 ms update rate; GEN1 ECUs support one at 2 ms.

Rocket Speed Shop is the official MaxxECU distributor for the Baltics. This is often the cheapest upgrade in the entire MaxxECU catalogue.

Why this module matters more than it looks

There are two ways to run out of ECU. You run out of injector and ignition drivers — you added cylinders, or you need staged injection — and that genuinely requires a bigger ECU. Or you run out of everything else: an analog input for oil pressure, a pulse input for a fourth wheel speed sensor, an output for a water-methanol pump, an H-bridge for a second throttle body.

The second case is far more common, and it does not require a new ECU. It requires an Expansion Module. A STREET with an Expansion Module has more analog inputs than a RACE does on its own, at a fraction of the cost difference.

Who the Expansion Module is for

• MINI and STREET owners who have run out of inputs. The MINI has 2 spare analog inputs, STREET has 2. One module takes that to 14.
• Anyone adding sensor-based protection strategies — oil pressure, oil temperature, fuel pressure, gearbox temperature, differential temperature, fuel level, brake pressure, steering angle.
• Builds needing more wheel speed sensors for real four-wheel traction control — 4 pulse inputs handle VR or digital sensors up to 30 kHz.
• Drive-by-wire and motor control. Four H-bridges at up to 15 A can drive bidirectional motors — a second throttle body, an electronic wastegate, a variable intake — or run as high-current single-ended outputs.
• GEN2 owners building something large. Four modules on a GEN2 ECU adds 48 analog inputs, 16 pulse inputs, 16 × 12 V outputs and 16 H-bridges.
• Anyone who wants to put the electronics near the sensors. IP68 and Superseal means the module can live in the engine bay, cutting long sensor wire runs down to a single CAN pair.

Key features

Twelve analog inputs

Accepts 0–5 V analog or digital signals up to 24 V, with a 3 V digital threshold and selectable 2.5 kΩ 5 V pull-up resistors. Update rate is selectable up to 2 kHz with 200 kΩ input resistance. Switches, buttons and other slow signals run in digital mode. One limitation worth knowing: ethanol content sensors are not supported on the analog inputs — use the pulse inputs for those.

Four pulse inputs

Digital or VR signals up to 200 V and 30 kHz, 62 kΩ input resistance, with selectable digital, VR or custom thresholds. Transmitted to the ECU at up to 1 kHz. This is where wheel speed sensors, flex fuel sensors and frequency-output sensors belong.

Four 12 V sourcing outputs

Active = 12 V, off = floating. 5 A continuous each, protected against overload and short circuit, with 30 V flyback protection. PWM up to 20 kHz.

Four H-bridge outputs

12 V push-pull half-bridge outputs. Active = 12 V, off = ground. For a bidirectional motor such as a throttle body, connect the load between two H-bridge outputs; for a general load, connect between one output and ground. Overload and short-circuit protected with PWM current limiting, selectable 7.5–15 A limit and 10 A continuous capability. PWM up to 20 kHz.

Zero CAN configuration

The module integrates with MTune seamlessly — no manual CAN message setup. Its inputs and outputs appear as native channels. If you do want manual control, or want to use more modules than the pre-defined limits allow, user-defined CAN configuration is supported and works with any ECU brand.

Built for the engine bay

IP68 black powder-coated aluminium, Superseal 1.0 automotive connectors, every input and output protected against overvoltage, reverse polarity, overload and short circuit. 6–22 V operating voltage, ARM dual-core CPU, 195 g, 80 × 138 × 35 mm.

MaxxECU Expansion Module full specifications

Expansion Module or a bigger ECU?

Buy the Expansion Module if…

You need inputs, general-purpose outputs or motor drivers. This covers most upgrade requests. Sensors, switches, pumps, solenoids, fans, extra wheel speed sensors, a second throttle body — all of it. One module on a STREET or SPORT is dramatically cheaper than moving to a RACE or PRO.

Buy a bigger ECU if…

You need more injector or ignition drivers, more sequential cylinders, knock sensor inputs, native EGT inputs or a second wideband channel. The Expansion Module does none of these. Specifically:

• More cylinders sequentially → STREET (6), RACE or GEN2 TRACK (8), PRO or GEN2 RACE (12)
• Knock control → RACE, GEN2 TRACK, GEN2 RACE or PRO
• Native EGT inputs → RACE (8), GEN2 RACE (8 at 200 Hz), PRO (12)
• Dual wideband → GEN2 TRACK, GEN2 RACE or PRO

Buy the PDM20 instead if…

What you actually need is switched power capacity rather than signal I/O. MaxxECU PDM20 gives 20 outputs at up to 230 A total with per-channel current monitoring, adjustable overcurrent protection and CAN keypad support. The Expansion Module is for signals; the PDM20 is for power. Many serious builds use both.

Which Expansion Module kit do you need?

The module itself is identical in both kits — what differs is how you wire it up.

• Expansion Module with connector kit — the module plus the Superseal 1.0 connector and terminals. Choose this if you are building your own loom and want to cut wires to exact length.
• Expansion Module with 5 m flying lead harness — the module with 5 metres of pre-terminated labelled cable already in the connector. Choose this if you would rather not crimp a connector by hand, or if the module is mounting some distance from the ECU.

The Expansion Module harness is also sold separately if you already have the module and want to add or replace the loom.

Frequently asked questions

Does the Expansion Module work with my MaxxECU?

Yes. It works with every MaxxECU, from MINI to GEN2 RACE, over the CAN bus.

How many Expansion Modules can I use?

Up to four on a GEN2 ECU using the pre-defined configuration, or one on a GEN1 ECU. With user-defined CAN configuration, any number can be used on any ECU — including other brands.

Does the Expansion Module add injector or ignition outputs?

No. It adds analog inputs, pulse inputs, 12 V sourcing outputs and H-bridge outputs. More injector or ignition drivers require a larger ECU.

Can I connect a flex fuel sensor to the Expansion Module?

Yes, but to a pulse input, not an analog input. MaxxECU specifically note that ethanol content sensors are not supported on the analog inputs.

Can the H-bridges drive a drive-by-wire throttle body?

Yes. Connect the throttle motor between two H-bridge outputs for bidirectional control, with selectable 7.5–15 A current limiting and 10 A continuous capability.

Can I use it for EGT on a GEN2 TRACK?

Indirectly, yes. The GEN2 TRACK has no native thermocouple inputs and reads EGT through 0–5 V amplifiers on its analog inputs — and an Expansion Module adds 12 more analog inputs to host those amplified channels.

Do I need to configure CAN messages manually?

No. The module integrates directly into MTune with no manual CAN message configuration — its I/O appears as native channels. Manual configuration is available if you want it.

Is the Expansion Module waterproof?

Yes. IP68-rated black powder-coated aluminium with Superseal 1.0 connectors, so it can be mounted in the engine bay close to the sensors it reads.

Where can I buy a MaxxECU Expansion Module in the Baltics?

Rocket Speed Shop is the official MaxxECU distributor for Estonia, Latvia and Lithuania.

Explore the rest of the MaxxECU range

MINI · STREET · SPORT · RACE · GEN2 TRACK · GEN2 RACE · PRO · PDM20.

Shop MaxxECU Expansion Module at Rocket Speed Shop →