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Holley EFI 558-420 Terminator® EFI Wiring Harness - Truck Part Superstore
Here's What OUR CUSTOMERS Have to Say:

Since 2018, We've Shipped Over 35,000 Automotive Parts to Canadian Customers.

4.6/5

+3,076 Verified Reviews
TH Verified

Easy to find and order. Customer service was responsive and helpful. It fit my vehicle and is protecting the back of it very well

Cory C. Verified

Specific parts for my vehicle were easy to find Shipping was good and website is clear and easy to use

Terrance O. Verified

Very happy with the running boards, and the shipping was prompt.

Jason Verified

Super easy, discount code worked well for my order

Ken A. Verified

I will buy from here again.

Justin L. Verified

Easy to use site, comprehensive descriptions. Relevant results

Mitchell D. Verified

Quick shipping, good prices. Great selection of products.

Frank J. Verified

Super easy, discount code worked well for my order

Shane Verified

Easy buying process. Fast shipping. Lots of selection!

Errol M. Verified

Great prices looking forward for possible tonneau cover from your site

Clint K. Verified

Quick response and went the extra mile to answer my questions. Very professional and knowledgeable, having nothing but good things to say about the team at TPS

Wade O. Verified

Fast and Quick,easy to understand The product was excellent and packaged extremely well, I would recommend them to all my friends.

Vern H. Verified

The staff was very helpful and the price point is fair. Rafael was very accomodating and responsive to request to cancel order and reorder a different tuner.

Jonathan A. Verified

Excellent service and price is good too Thanks.

Julien M. Verified

Good service !

JS Verified

Purchasing process was extremely fast and simple, and the product came on time. 5/5 stars.

Holley EFI 558-420 Terminator® EFI Wiring Harness

SKU ds_BBVL_558-420
Proudly Canadian

Albertan Owned

Supporting Canadian truckers since 2018
Secure Payments

Financing Available

SSL encrypted checkout with financing options
Trusted Brands

Top-Quality Suppliers

Authorized dealer for Fox, Bilstein, BFGoodrich & 50+ brands
$106.66 - $106.66
$106.66
$106.66
$106.66 - $106.66
$106.66
Availability:
4+ in stock
Description
PN 558-420 contains 5 extra input/output wires that the base Terminator EFI harness does not contain. It contains Input wires for Inputs 1-4. It contains one wire for Output 2. These inputs and outputs can perform features and functions that must be programmed via Holley EFI laptop software. The software also contains instructions on how to program these.
Resources
Installation Instructions

Specifications

Description_ASC Holley Performance Emission Code 5: This part is legal for sale or use on Emissions Controlled Vehicles; Uncontrolled (Non-Emissions Controlled) Vehicles; and Racing Use Only Vehicles because it does not affect vehicle emissions and is not covered by emissions regulations
Description_DEF Engine Control Module (ECM) Wiring Harness
Description_DES Terminator® EFI Wiring Harness
Description_EXT Terminator® EFI Wiring Harness; Incl. 4 Extra Input Wires And 1 Extra Output Wire; Must Be Programmed Via Holley EFI Software;
Description_FAB 205 lb./hr. Injector Harness
Description_FAB Can Perform Features And Functions
Description_INV TERMINATOR EFI I/O KIT
Description_LAB Proposition 65
Description_MKT PN 558-420 contains 5 extra input/output wires that the base Terminator EFI harness does not contain. It contains Input wires for Inputs 1-4. It contains one wire for Output 2. These inputs and outputs can perform features and functions that must be programmed via Holley EFI laptop software. The software also contains instructions on how to program these.
Description_SHO EngControlModuleWrHn
height 1.6
length 5.0
WARNING CA Proposition 65 Yes
WARNING CA Proposition 65 Message WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov
weight 0.6
width 7.6
Fitment
More from this Collection
Here's What OUR CUSTOMERS Have to Say:

Since 2018, We've Shipped Over 35,000 Automotive Parts to Canadian Customers.

4.6/5

+3,076 Verified Reviews
TH Verified

Easy to find and order. Customer service was responsive and helpful. It fit my vehicle and is protecting the back of it very well

Cory C. Verified

Specific parts for my vehicle were easy to find Shipping was good and website is clear and easy to use

Terrance O. Verified

Very happy with the running boards, and the shipping was prompt.

Jason Verified

Super easy, discount code worked well for my order

Ken A. Verified

I will buy from here again.

Justin L. Verified

Easy to use site, comprehensive descriptions. Relevant results

Mitchell D. Verified

Quick shipping, good prices. Great selection of products.

Frank J. Verified

Super easy, discount code worked well for my order

Shane Verified

Easy buying process. Fast shipping. Lots of selection!

Errol M. Verified

Great prices looking forward for possible tonneau cover from your site

Clint K. Verified

Quick response and went the extra mile to answer my questions. Very professional and knowledgeable, having nothing but good things to say about the team at TPS

Wade O. Verified

Fast and Quick,easy to understand The product was excellent and packaged extremely well, I would recommend them to all my friends.

Vern H. Verified

The staff was very helpful and the price point is fair. Rafael was very accomodating and responsive to request to cancel order and reorder a different tuner.

Jonathan A. Verified

Excellent service and price is good too Thanks.

Julien M. Verified

Good service !

JS Verified

Purchasing process was extremely fast and simple, and the product came on time. 5/5 stars.

Need Help? We've Got Answers.

Find quick solutions to the most common questions about shipping, returns, compatibility, and support.

How do I know if a part fits my truck?

Use our vehicle filter by entering your truck’s year, make, and model. If you're unsure, our support team is happy to help.

Do you ship across Canada?

Yes! We ship to all provinces and territories in Canada. Free shipping is available on qualifying orders.

How long will it take to receive my order?

Delivery times vary depending on your location and item availability. Most orders arrive within 2–7 business days.

What is your return policy?

We accept returns within 30 days of delivery, as long as the item is unused and in its original packaging.

How can I contact customer support?

You can reach us via email, phone, or through the contact form on our website. Our team is ready to assist you.

Still have questions?

Our team is here to help — reach out and we'll get back to you as soon as possible.

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ABOUT US

It all started in 2018, with a simple idea: to create an online haven for automotive enthusiasts.

I wanted a place where people could find not just truck parts, but a wide array of automotive products, including overlanding gear, performance parts, car accessories, and
items for Jeep and SUV owners.

That's how Truck Part Superstore came to life.

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