A black Holley Terminator X handheld controller with a screen, labeled &
Black Holley EFI 3.5 touchscreen programmer cable with connectors on a white background
A black Terminator X LCD tuning display with a dark screen and a visible cable, shown on a plain white background.

Holley EFI Terminator X 3.5" LCD Touchscreen Handheld Controller

553-201

Regular price$374.95
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Shipping calculated at checkout.


The Holley EFI Terminator X 3.5" LCD Touchscreen Handheld Controller gives you complete control of your Terminator X EFI system without requiring a laptop. Featuring a full-color backlit touchscreen, this handheld allows you to perform tuning adjustments, monitor engine vitals, configure ECU settings, record datalogs, update firmware, and review system diagnostics—all from an intuitive interface.

Whether you're performing an initial startup, making track-side tuning changes, or simply monitoring engine performance, the Terminator X handheld provides quick access to fuel, ignition, idle, and closed-loop tuning parameters. The customizable gauge layouts make it easy to keep an eye on critical engine data while the built-in SD card support allows datalogging and firmware updates in minutes.

Includes:

  • (1) Holley EFI 3.5" LCD Touchscreen Handheld Controller
  • Mounting Sleeve
  • Power Harness
  • Extension Harness
  • SD Card
  • User Manual CD

Specifications
Specification Details
Manufacturer Holley EFI
Part Number 553-201
Display Size 3.5 in. Full-Color Backlit LCD Touchscreen
Product Type Handheld EFI Controller
Tuning Capability Fuel, Spark, Idle, Closed Loop, Learn, IAC, Outputs
Data Logging Internal ECU Datalogging with SD Card Support
Firmware Updates Supported via SD Card
Screen Dimensions 3.35" W × 2.85" H × 0.70" Thick
Mount Sleeve Dimensions 3.625" W × 2.925" H × 1.00" Thick

Fitment
  • Compatible only with Holley Terminator X EFI systems.
  • Works with Terminator X and Terminator X Max ECUs.
  • Ideal as a replacement handheld or additional controller.
  • Allows laptop-free tuning, monitoring, and diagnostics.
  • Legal for use on emissions-controlled vehicles, non-emissions-controlled vehicles, and racing-only vehicles.

Tech Insight

1. What can I tune with the handheld?

The handheld provides access to basic and advanced tuning functions including fuel, ignition timing, idle speed, closed-loop fuel control, fuel learning, IAC settings, rev limiters, engine setup, ignition setup, and programmable outputs.

2. Can I tune without a laptop?

Yes. The handheld was designed specifically for laptop-free tuning, allowing you to make adjustments directly from the touchscreen.

3. Can it display live engine data?

Absolutely. The display features multiple preconfigured gauge layouts and customizable monitoring screens so you can watch critical engine parameters in real time.

4. Does it support data logging?

Yes. The handheld can configure ECU datalogging, save logs to the included SD card, transfer calibration files, and perform ECU firmware updates.

5. Is this compatible with Sniper or HP EFI?

No. This handheld is designed exclusively for Holley Terminator X EFI systems and is not compatible with Sniper EFI, HP EFI, or Dominator EFI systems.