Nexus S2 Plug-n-Play Adapter Harness Kit – Mazda MX-5 (90-97 / 99-05)

The Ultimate Standalone ECU Solution

Take your Miata’s engine management to the next level with the Haltech Nexus S2 Plug-n-Play Adapter Harness Kit, available for both NA (1990-1997) and NB (1999-2005) Mazda MX-5 models.

This harness kit transforms your Miata into a fully modernized, precision-tunable platform. Designed to integrate seamlessly with the Haltech Nexus S2 VCU (Vehicle Control Unit), it offers a true plug-and-play experience — no cutting, splicing, or repinning required. Simply connect the factory ECU plugs to the adapter harness, connect the Nexus S2, and unlock full standalone control in minutes.

Key Features

• Direct OEM Integration: Uses factory connectors for a clean, reversible installation.

• Full ECU Control: Manage fuel, ignition, boost, DBW, flex-fuel, CAN integration, advanced I/O, and more.

• Premium Construction: Professionally loomed, labeled, and terminated using motorsport-grade components.

• Future-Ready Platform: Supports Haltech CAN devices, wideband controllers, and race-grade sensors.

• Dual Application Availability:

  • 1990-1997 Miata (NA)

  • 1999-2005 Miata (NB)

Why Choose the Fab9 Solution?

We include a 30 minute live session! As Mazda performance specialists, Fab9 Tuning ensures known injector data, sensor configuration and we get you running and ready for tuning.  From daily-driven street cars to competition track machines, you can continue tuning with us remotely or come visit us on the dyno here in Tennessee. Pairing Haltech’s Nexus S2 intelligence with Fab9’s Miata expertise gives you the most comprehensive management system available for the MX-5 platform.

Compatibility:

• Mazda MX-5 Miata 1990–1997 (NA)

• Mazda MX-5 Miata 1999–2005 (NB)

Package Includes:

• Haltech Nexus S2 Plug-n-Play Adapter Harness

• Installation guide and setup support via Fab9 Tuning

Notes: Does not support USDM OBDII 96-97, Special Edition SE and Anniversary models. All manual transmission 1.6L variants will require the factory throttle position sensor to be unplugged and removed. A full-range throttle position sensor alternative must be installed for correct functionality. Failure to do so will result in erratic behavior of the ECU at wide-open throttle along with damage to the ECU. Using a Nexus S2 instead of a Nexus S3 will reduce some of the car's factory functionality. Refer to the quick start guide for details.