How to Remove a Crankshaft Sensor from a Nissan Altima 2003

As emissions became stricter throughout the 1970s, car manufacturers saw their big V-8s barely cresting 150 horsepower, and they knew that changes needed to be made. Entering the 1990s, electronic controls on engines helped keep emissions low while keeping engine output high by way of small, on-the-fly adjustments. The trade-off was that these electronically controlled vehicles required many things to operate correctly for the vehicle to run at its best. One of these electronic controls on the 2003 Altima, the crankshaft position sensor, constantly reads the crankshaft's position and relays that information to the vehicles computer; the computer then adjusts the ignition timing as needed. Replacing this sensor is straightforward on both the available engine variants on the 2003 Altima.

Instructions

1

Raise the front of the Altima with a floor jack and slide jack stands under the subframe. Lower the vehicle onto the jack stands.

2

Crawl under the front of the vehicle, so that you are positioned under the drivers side of the engine.

3

Find the crankshaft position sensor plugged into the end of the upper oil pan, near the front of the engine compartment on the 3.5-liter engine, and on the engine block nearest the rear of the engine compartment, just under the starter, on the 2.5-liter engine.

4

Pull upward on the locking tab on the crankshaft position sensors wiring harness and unplug the harness from the sensor.

5

Remove the crankshaft position sensor-retaining bolt with a ratchet and socket, and pull it from the engine.

6

Set a new rubber seal, included with the new sensor, on the 3.5-liter engines new crankshaft position sensor. Lubricate the O-ring on the new crankshaft position sensor for the 2.5-liter engine with fresh 5W-30 engine oil.

7

Guide the new crankshaft position sensor into the engine and hand-thread its retaining bolt. Tighten the crankshaft position sensor bolt to 5 foot-pounds on the 2.5-liter engine or to 7 foot-pounds on the 3.5-liter engine, using a torque wrench and socket.

8

Plug the wiring harness into the receptacle on the crankshaft position sensor.

9

Raise the vehicle from the jack stands with a floor jack and remove the jack stands. Lower the Altima to the ground.