The Link ECU Honda K20X (Link’s model code HC20X, order code 237-4000) is a G4X plug-in standalone ECU for the K20A engine family. The PCB mounts inside the factory ECU enclosure and connects to the unmodified factory harness, replacing the stock engine computer with full standalone engine management — sequential fuel, direct spark, closed-loop VTEC/VTC cam control and onboard data logging — without cutting a single wire. Link lists it as the CIVICLink K20X; it launched as the HC20X and both names refer to the same 237-4000 unit.
It suits K20A/K20A2/K20A3 Integra DC5, Civic EP3 and Acura RSX road and race cars, and is a popular K20 standalone ECU choice for K20/K24 swaps run on a 2002–2004 RSX-spec harness. Most factory functions are retained (see FAQ).
Before ordering: check that your car’s ECU connector matches the header in the product photo — the K20X uses the 2002–2004 RSX-style ECU header. This ECU works with manual transmissions only.
CAN note: the K20X uses the newer 4-pin powered CAN connector. Use the CANJST4 cable (101-0198) for CAN devices — it carries CAN plus a fused 12 V supply, and the older CANPCB cable is not compatible.
Vehicle Fitment
| Vehicle | Engine | Years |
|---|---|---|
| Honda Integra Type R DC5 | K20A / K20A2 / K20A3 | 2002–2004 |
| Acura RSX | K20A / K20A2 / K20A3 | 2002–2004 |
| Honda Civic Type R EP3 | K20A | 2001–2005 |
| Honda Civic Si/SiR | K20A3 | 2001–2005 |
| Honda Civic DX/LX/HX | D17A1 / D17A2 / D17A3 | 2001–2005 |
| Honda CR-V | K24A1 | 2002–2004 |
Manual transmission only. Automatic-equipped cars are not supported.
Key Specifications
| Property | Value |
|---|---|
| SKU | 237-4000 |
| Link model | CIVICLink K20X (HC20X) |
| Platform | G4X plug-in |
| Injection drivers | 8 high-current (Inj 5–8 available for staged injection with minor rewiring) |
| Ignition channels | 8 (4 used for coils; spares drive CE light, A/C clutch, intake runner, EVAP) |
| Auxiliary outputs | 8, all PWM capable |
| Analog inputs | 12 × 0–5 V + 4 temperature inputs |
| Digital inputs | 11, up to 10 kHz |
| Knock control | 2 knock inputs with windowing — uses the factory knock sensor |
| Onboard MAP sensor | 7 bar absolute (6 bar boost), jumper-selectable vs factory MAP |
| Cam control | Closed-loop VTEC + VTC |
| CAN | 2 buses; 4-pin powered CAN port (CANJST4 cable) |
| Data logging | 512 MB onboard, up to 250 channels at up to 1 kHz/channel |
| E-throttle | Internal controller + dedicated e-throttle expansion connector |
| Operating voltage | 8–22 V |
| Software | PCLink G4X (free), USB tuning; base configuration pre-loaded |
| Transmission | Manual only |
What You Can Do With It
- Tune fuel and ignition in up to 6D maps with QuickTune and individual cylinder correction
- Run closed-loop VTEC and VTC cam control natively on the factory solenoids
- Run up to 6 bar of boost on the onboard 7 bar MAP sensor — no external sensor needed
- Control 5D boost with 3 switchable tables, antilag, launch control and flat shift
- Log 512 MB of data onboard at up to 1 kHz per channel, then analyse it in PCLink
- Add staged injection using Inj 5–8 on the main header with minor harness rewiring
- Convert to drive-by-wire via the dedicated e-throttle expansion connector (Aux 9/10)
- Connect a wideband lambda, dash or EGT amplifier over CAN with a single CANJST4 cable
- Keep factory A/C, temperature gauge, radiator fan, tacho and fuel pump control working
Link Plug-in ECUs for Honda
| Model | Vehicle | Engine |
|---|---|---|
| LinkECU Honda K20X PlugIn | Integra DC5, Civic EP3, RSX | K20A / K24A1 / D17A |
| LinkECU PlugIn Honda S2000 | S2000 AP1, AP2 (2005) | F20C / F22C |
| LinkECU PlugIn Honda Civic Gen 6 | Civic 1996–98 | B/D-series |
| LinkECU PlugIn Honda Civic Gen 5 | Civic 1992–95 | B/D-series |
Recommended Accessories
- LinkECU CANJST4 CAN Cable (101-0198) — required for connecting and powering CAN devices from the 4-pin powered CAN port
- LinkECU CAN Lambda Controller — wideband lambda via CAN, powered directly through the CANJST4 cable
- LinkECU XS Expansion Loom — brings the expansion connector I/O (Aux 9/10, An Volt 3–6, DI 6–9) out to flying leads
- LinkECU E-Throttle Upgrade on G4X PlugIn ECU — for drive-by-wire conversions
Frequently Asked Questions
Does the Link K20X work with an automatic transmission?
No. The K20X supports manual transmissions only — this applies to every listed application, including the CR-V K24A1 and D17 Civics.
How do I know the K20X will plug into my car?
Check that your factory ECU connector matches the header shown in the product photo before ordering. The K20X uses the 2002–2004 RSX-style ECU header; Honda used several header variants across these years and markets.
Can I use the K20X for a K20 or K24 engine swap?
Yes — it is a common choice for K-swaps wired with a 2002–2004 RSX-spec engine harness, giving full standalone management with plug-in convenience. The official fitment list covers factory-chassis installs; for a swap, build or buy the harness to 02–04 RSX spec.
Link K20X or Hondata KPro — which one?
KPro is the lower-cost option for street builds: it reflashes a donor 02–04 ECU and keeps OEM driveability with a large Honda tuning base. The K20X is a full standalone: configurable knock control, 512 MB / 250-channel logging, antilag, launch control, flat shift, staged injection, two CAN buses for dash/lambda/PDM integration, and e-throttle capability. For boosted, motorsport or heavily instrumented builds, the K20X is the step up.
Does it come with a base map?
The ECU ships with a base configuration pre-loaded, and PCLink includes model-specific sample maps. Trigger, MAP and TPS calibration must be verified before first start, and the car must be tuned before driving in anger.
Do factory functions keep working?
Most do: fuel pump, idle control, radiator fan, tacho, A/C clutch, alternator control, EVAP purge and the temperature gauge (via K-Line) are all supported on the factory harness. The immobiliser light may continue flashing on some cars — Link tech support has a software fix.
How much boost can the onboard MAP sensor read?
The onboard sensor reads 7 bar absolute — about 6 bar of boost. It is jumper-selectable against the factory MAP sensor. Early HC20X units shipped with a 4 bar sensor; 7 bar units carry a sticker on the bottom board.
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