439-5039 Water-in-Fuel Sensor for CAT 320 323 336 340

439-5039 Water-in-Fuel Level Sensor for Caterpillar Equipment

The 439-5039 sensor is used in Caterpillar fuel systems to monitor liquid level associated with water separation from the fuel. It is commonly identified as a fuel water level sensor, water-in-fuel sensor or fuel water separator level sensor rather than a fuel tank gauge sender.

Caterpillar application references include excavators such as CAT 320, 323, 326, 330, 335, 336 and 340, together with other equipment including D6K2 tractors and selected wheel loader applications. Because this sensor is application-specific, the old part number and installed configuration should be checked before ordering.

What Does the 439-5039 Sensor Monitor?

439-5039 is associated with the fuel water separation system. Its purpose is to provide an electrical level signal when the monitored liquid reaches the sensing condition used by the machine warning system.

439-5039 Identification Details Before Ordering

Useful Caterpillar reference information for 439-5039 includes 12/24V DC operation and approximately 7.2 inches of wire length. The assembly includes the sensor, wiring lead and electrical connector.

If the original number cannot be read clearly, compare these details with the removed sensor:

• Electrical connector shape and terminal arrangement.

• Wire length and routing from the sensor body.

• Sensor mounting and threaded connection.

• Fuel water separator or tank position where the sensor is installed.

• Complete CAT machine and engine model.

Is 549-6892 the Same as 439-5039?

549-6892 is frequently listed together with 439-5039 in aftermarket replacement catalogs, and the two numbers share a number of Caterpillar engine and machine applications. However, they should not be treated as universally interchangeable from the number alone.

If your old sensor or purchase record shows 549-6892, send the original sensor photo, connector, mounting details and machine model before quotation. We can compare the physical configuration instead of assuming that every 439-5039 and 549-6892 installation is identical.

C7.1 C4.4 and Excavator Application Checking

439-5039 appears in Caterpillar applications covering C7.1 and C4.4-related equipment, as well as a wider range of industrial engines and construction machines. The same sensor number can therefore appear on excavators, tractors, compactors, generator sets and loaders.

For excavator inquiries such as CAT 320, 323, 336 or 340, provide the full machine model and serial information when available. This helps avoid incorrect matching where the same model family has different fuel-system arrangements or has been repaired with a later replacement component.