Kooks O2 Extension Harness Shelby GT500 12" Extension Harness (6-Pin)

12 Inch 6 Pin O2 Extension Harness Engineered for the Shelby GT500 Header Installation

The CAS-109203 is a 12 inch O2 sensor extension harness with a 6 pin connector designed specifically for the Shelby GT500, providing the correct length and connector configuration to properly extend the O2 sensor wiring after long tube header installation on the GT500 platform. The Shelby GT500 uses a 6 pin O2 sensor connector format rather than the 4 pin connectors found on many other Ford applications, which is why a GT500 specific harness is required rather than a generic O2 extension. Using the wrong connector type or an improperly sized extension creates wiring routing issues and can compromise the O2 sensor signal quality that fueling and tune accuracy depend upon.

At 12 inches, the CAS-109203 provides the extension length needed to reach the relocated O2 sensor position created by Kooks long tube headers on the GT500 without excess wire that must be bundled and managed under the hood. The plug and play design eliminates splicing, soldering, and any guesswork about correct connector pinout. For GT500 owners installing Kooks headers, this harness is the completing piece of the electrical installation that should be ordered alongside the headers themselves to ensure the full system is ready to install on the day the work begins.

Key Features

• 12 inch extension length matched to GT500 O2 sensor relocation distance with Kooks headers
• 6 pin connector configuration specific to the Shelby GT500 O2 sensor harness
• Plug and play installation, no splicing or soldering required
• Maintains full electrical integrity of the O2 sensor circuit
• Designed for use with Kooks long tube headers on the Shelby GT500
• Prevents check engine lights caused by stretched or improperly connected O2 wiring

What's Included

• 1 x this harness 12 inch 6 pin O2 sensor extension harness for Shelby GT500

Specifications

Frequently Asked Questions

What vehicles does this harness fit?
This harness is designed for the Ford Shelby GT500. Confirm with Kooks which specific GT500 model years are covered by this part number for your application.

Why does the GT500 need a 6 pin O2 connector?
The Shelby GT500 uses a wideband or more complex O2 sensor circuit than many other Mustang models, requiring a 6 pin connector to carry the additional signal and reference circuits. Using a standard 4 pin extension on a 6 pin application will result in incorrect sensor readings and check engine lights.

Is this harness plug and play?
Yes. This harness uses factory compatible 6 pin connectors on both ends, allowing it to be plugged in line between the factory harness and the O2 sensor without any cutting or soldering.

How long is this harness?
The extension harness is 12 inches long, sized to bridge the gap between the factory harness and the O2 sensor's new position created by Kooks long tube headers on the GT500.

Will this harness trigger a check engine light?
When properly installed with a compatible tune, this harness will not cause O2 sensor related check engine lights. The extension maintains the full electrical integrity of the 6 pin O2 circuit.

Is this harness sold as a single harness?
Yes. This harness is a single harness. Determine how many O2 sensors require extension on your specific GT500 header application and order accordingly.

Should I install this harness before or after a tune?
Install this harness before tuning so the ECU tune can read the O2 sensors accurately from the start of the tuning process.

Does a stretched O2 connection cause problems?
Yes. Stretching a 6 pin connector places mechanical stress on the terminals, which can cause intermittent contact and inaccurate O2 readings. Inaccurate O2 readings cause fueling errors and check engine lights.

Can this harness be used on a non GT500 Mustang?
This harness uses a GT500 specific 6 pin connector. It is not compatible with standard 4 pin O2 sensor harnesses found on other Mustang models. Use the EX682-Z or CAS-104326 for other applications.

Is this harness included with Kooks GT500 header kits?
Some Kooks header kits include O2 extensions. Verify whether your specific Kooks GT500 header kit includes O2 extensions before ordering separately to avoid duplicate purchases.

Installation Instructions

1. Confirm Kooks long tube headers are fully installed on the GT500 before addressing O2 sensor wiring.
2. With the ignition off, locate the 6 pin O2 sensor factory harness connector at the sensor needing extension.
3. Unplug the factory harness from the O2 sensor at the original connector location.
4. Connect one end of this harness to the factory 6 pin harness connector.
5. Route the 12 inch extension away from header primary tubes and heat sources, securing with tie wraps or clips as needed.
6. Connect the opposite end of this harness to the O2 sensor in its new position.
7. Confirm the connection is fully seated at both ends before starting the vehicle.
8. After a professional ECU tune, verify no O2 sensor related check engine lights are present.

Prop 65 Warning

WARNING: This product can expose you to chemicals known to the State of California to cause cancer, birth defects or reproductive harm. For more information go to www.P65Warnings.ca.gov.