6.9L, 7.3L IDI Tachometer Sensor

How to Replace the Tach Sensor on a 6.9/7.3 IDI Diesel

If the tachometer on your 6.9L or 7.3L IDI ceases to function properly or altogether, the most likely culprit is the tach sensor. The tach sensor is located on the injection pump gear cover on the front of the engine. The part number, which includes the sensor and pigtail connector, is E5TZ-17B384-A. Replacing the sensor only takes a few minutes and typically cures tachometer issues.

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Tach sensor location

• The tach sensor for the 6.9/7.3L IDI is located towards the front of the engine on the injection pump gear housing (red arrow in image).

• If you'd prefer to test the tach sensor before replacing, check resistance across the two sensor wires with a multimeter. If the resistance measures between 2,000 and 3,000 Ohms, the sensor should be good.

Ford E5TZ-17B384-A

• This is the tach sensor, Ford part number E5TZ-17B384-A. It's a very primitive, simple sensor that reads a magnet on the injection pump gear as it rotates. Every time the magnet passes this sensor, it triggers it and this pulse is what drives the tachometer.

Tach sensor removal

• To remove the sensor, first disconnect the connector (red arrow, hidden behind the heater hose in the image). There are two clips that secure the connector; a small flathead screwdriver can be used to release the two safety clips.

Tach sensor replacement

• At just under $75 for a new sensor, it is not a cheap item. As you can see, this sensor has seen better days, and the previous owner(s) have performed some fancy tape work in an attempt to keep the original one working. Once the sensor has been disconnected, use a 1 inch wrench to remove it.

 

New tach sensor prior to installation

• Apply a small amount of fresh motor oil to the o-ring (red arrow in image) before installing the new sensor; this ensures a positive seal.

Tach sensor installed on 6.9 IDI diesel

• Installation of the new sensor is reverse. Thread it in by hand to ensure it does not cross thread, then snug it up with your wrench. Finally, plug the connector into the harness. You may also want to wrap the sensor's wires with electrical tape to protect it from chafing in the future.