Flagship platform / 2001-2006
The golden-era Subarus deserve better than abandonware.
Most tools for the 2002-2005 WRX generation stopped moving years ago. PulseWidth treats these 16-bit ECUs as a first-class platform: 134 calibrations mapped, flashing through the stock OBD-II port, full diagnostics, and live tuning that changes maps while the engine is running.
WRX · STi · Forester Turbo · Legacy B4 · Outback H6
134
HC16 calibrations
Individually mapped stock calibrations across five model families and six markets.
5
Model families
WRX, STi, Forester Turbo, Legacy/Liberty B4, and Outback H6.
0
Soldering irons
Read, flash, log, and diagnose through the factory OBD-II port. No chip pulls, no daughterboards.
29
USDM WRX cals
Every 2002-2005 USDM WRX calibration in the set is defined and editable.
Compatibility
Find your car.
These are the Subarus that shipped with the 16-bit HC16 ECU. Coverage below comes straight from our definition set, one mapped calibration at a time.
| Model | Chassis | Years | Markets | Notes |
|---|---|---|---|---|
| Impreza WRX | GD / GG (bugeye, blobeye) | 2002-2005 | USDM, JDM, EDM, ADM, SADM | The flagship. All 29 USDM calibrations defined, with live tuning on supported cals. |
| Impreza WRX STi | GDB | 2001-2006 | JDM, EDM, ADM | Includes AVCS-equipped models. The USDM 2004+ STi uses a newer 32-bit ECU outside this platform (dedicated edition planned). |
| Forester Turbo | SF5 / SG5 (S/tb, early XT) | 2001-2003 | JDM, EDM, ADM, SADM | The USDM 2004+ Forester XT uses a newer 32-bit ECU outside this platform. |
| Legacy / Liberty B4 | BE / BH (twin turbo) | 2002-2003 | JDM, ADM | Includes BH wagons and the 3.0 DOHC six. |
| Outback H6 3.0 | BH / BP (incl. VDC, L.L.Bean) | 2001-2004 | USDM, AUDM, JDM | Naturally aspirated six: diagnostics, logging, and calibration access. |
Not sure which ECU your car has? Plug in and PulseWidth identifies it automatically. The app reads the calibration ID from the ECU and tells you exactly what is supported before anything is written.
What you get
Modern tooling for a 16-bit ECU.
Full ROM editing, mapped by hand
Boost control, fueling, ignition timing, compensations, sensors, limits, and diagnostic toggles: every table in the definition set was mapped and verified against real ROM dumps, not copied from decade-old spreadsheets. Heat maps, 2D and 3D views, compare mode, and map tracing come standard.
Flash through the factory port
Reflash your ECU through the stock OBD-II connector with a standard J2534 cable (Tactrix OpenPort 2.0 works out of the box). Before a single byte is written, PulseWidth runs a pre-flight checklist: ROM size and processor match, checksum validation, battery voltage, and a prompt to back up your stock ROM. Dry-run test writes, CRC compare, and read-back verify are built into the flash screen.
Live tuning: change maps while the engine runs
On supported calibrations, PulseWidth applies calibration changes in real time over the factory K-line. Adjust a cell, hear the engine respond. No standalone ECU, no piggyback, no flash-wait-restart loop for every iteration. When you're happy, commit the result to a permanent flash.
Live data and digital dashboards
Stream the channels these ECUs actually expose (RPM, load, timing, knock feedback, boost, temperatures), log them, replay them, and put them on a full-screen digital dash. Dozens of dash themes ship in the box, including layouts built for exactly this platform.
Diagnostics without the dealer
Read and clear trouble codes, check readiness, and watch sensors live: the same K-line session the factory tools used, minus the factory tools. DTC descriptions are built in, per calibration.
Your garage, organized
Every car, calibration, ROM revision, and tune session lives in one garage view. Auto-detect reads the ECU and matches it to the right definition so you never edit the wrong map for the wrong car.
Dash themes
Run it full screen on a laptop, tablet mount, or spare monitor.
Straight answers
Questions we actually get.
Is my car supported?
If it's a 2002-2005 WRX (any market), a 2001-2006 JDM/EDM/ADM STi, a 2001-2003 Forester Turbo, a 2002-2003 Legacy/Liberty B4 twin turbo, or a 2001-2004 Outback H6, it almost certainly runs the 16-bit HC16 ECU this platform targets. The fastest way to know for sure: connect with any J2534 cable and PulseWidth will read your ECU's calibration ID and tell you exactly what's supported.
What hardware do I need?
A Windows PC and a J2534 pass-through cable. The Tactrix OpenPort 2.0 is the reference cable and works out of the box. No ECU removal, no soldering, no eBay adapter roulette.
What is live tuning and does my car get it?
Live tuning lets PulseWidth change calibration values while the engine is running, over the factory K-line diagnostic port. It's supported on specific calibrations (2002-2003 USDM WRX today, with coverage expanding). The app tells you whether your calibration supports it the moment your ROM is loaded.
How safe is flashing a 20-year-old ECU?
Safer with guardrails than without. PulseWidth validates ROM size, processor type, and checksums before writing, checks battery voltage, prompts you to save a stock backup, and offers dry-run test writes and read-back verification. No tool can make flashing risk-free, but ours refuses to do the obviously dangerous thing.
My 2004-2005 USDM STi isn't listed. Why?
The USDM 2004+ STi shipped with a newer 32-bit ECU, which sits outside the classic HC16 platform. Same story for the USDM 2004+ Forester XT. Newer generations will get their own dedicated editions later; create a free account and you'll see the announcement when that happens.
Is this legal for my street car?
PulseWidth features that affect emissions systems are gated behind our compliance framework, and competition-use features require a signed competition-use agreement. Read our emissions compliance page for the details. We take this seriously so the platform stays available for everyone.
Your car has been waiting twenty years for this.
Create a free account, check your coverage, and see the ROM editor with your own calibration. When you're ready to flash, one license covers your vehicle for life.