Where is the crankshaft position sensor on 2004 Nissan Altima and how do you replace it?

Answer 1

The steps below are for a 2004 Nissan Altima with a 2.5 liter engine.

Nissan has a crank and cam sensor kit. I would not buy any aftermarket sensors because of the effort required to replace the sensors. (I do not work for Nissan). The information below is compiled of tips I found on the internet and my own experience. Even though these procedures may appear lengthy, it took me much longer to figure out the correct steps involved for this task.

Even though I have included all of the steps (and hints) I used... THIS IS NOT AN EASY JOB FOR THE "DO IT YOURSELFER"

CRANK SENSOR IS LOCATED AT FIRE WALL SIDE OF BLOCK BETWEEN MOTOR MOUNT AND FLYWHEEL. YOU GET TO IT FROM TOP.

Remove the (4) Allen head bolts that hold the plastic engine cover. Remove the air tube that connects the throttle chamber to air filter box. Pull off the valve cover breather hose with the air tube. Now place a drop light under the two rubber heater hoses (at the firewall on the drivers hand side), shining the light forward towards the back side of the block (below the intake runners). To see the crankshaft sensor and connector, look between the valve cover and the throttle chambers (intake runners) on the drivers side, look straight down toward the ground... look for the sensor with a black wire connector with a green tab on the side, held to the engine block with a gold colored 10mm hex headed bolt. You will need to view the sensor from this position as you are following the steps below to remove and install the crank sensor. There is a large wiring harness bracket attached to the transmission bell housing that was temporarily unbolted to aid with the removal and installation of the crank sensor.

What turned out to be the biggest problem was the connector securing the wiring harness to the sensor. Unlike the camshaft position sensor connector that is removed by squeezing in on a tab located at the top of the connector, the crank position sensor was secured to the harness via some green colored push button assembly. To remove the crank sensor connector, the green tab must depressed ALL THE WAY DOWN (towards the block) UNTIL THE GREEN TAB LOCKS INTO PLACE - REMAINING IN A "PUSHED IN" POSITION (You should hear a "click"). I was able to accomplish this by viewing the connector as described above and at the same time, reach around the back side of the engine using a 6" - 8" flat blade screw driver (with a large head) and push the green tab in towards the block until it locked into place. After the green tab was depressed and locked, (still viewing from above) I repositioned my hand holding a smaller flat blade screw driver to gently pry the connector off the sensor inserting the blade of the screw driver between the bottom of the connector and the crank sensor (a slight twist should do it). I do not recommend pulling on the connector wires or trying to pull the connector off with pliers as damage may result - because in my world of auto repair, if there is a chance that something will break because I am not careful... IT WILL BREAK! After you have removed the connector and while viewing from above, use a ¼" drive ratchet with a 6" extension and a 10mm socket to loosen the gold bolt holding the crank sensor in place. I recommend that you loosen the bolt with the socket, then reach your hand around to the connector and remove the bolt by hand. After the bolt is removed, use an 8" slip jaw pliers - set at its widest opening setting - to grab the sensor. First twist then pull out the sensor.

Be sure to clean the inside of the sensor's wiring connector with break cleaner spray and blow out with compressed air to get rid of any oil that may have leaked into the connector from the defective crank sensor... this is what probably caused the trouble code in the first place.

You are now ready to install the new crank sensor. If you purchased the crank and cam sensor kit from Nissan, make sure that sensor with white dot at bolt whole goes to the crank. Be sure to oil the rubber "O" ring. I was not able to get the green tab on the connector to snap back into place while the new sensor was installed in the block. I installed the connector to the sensor while it was out of the block - the green tab still did not pop back into its original position on its own - so...while the connector was installed as far down as I could push it, it used a small flat blade screw driver to push on the bottom of the green tab towards the top. That did the trick. While viewing from above, I placed the crank sensor back into the block. I was not able to get the rubber "O" ring to seat within the block by hand. I used the gold bolt to draw the sensor in while slowly tightening. HINT: I taped the outside of the washer of the crank sensor bolt to the 10mm socket to hold the bolt on place while I inserted the bolt into the block... you can do this by hand, but I didn't want to drop the bolt . I also taped the socket to the ratchet extension so the socket would not get stuck on the bolt (it's a snug fit down there).

If you were able to accomplish the above procedures, the cam sensor is a snap to remove in install. It is located in the driver's side portion of the head facing the wheel.

Remember to reinstall all brackets and items that were removed.

Good luck!

Many thanks to the author of this information. This was great help in changing the crank sensor or my Nissan. Only a couple of things I did different which may be of added benefit. 1): While you already have the 10mm socket down near the sensor go ahead and push the green button on the connector into the locked position. I found that the 10mm socket was just the right size to do this. 2): I found it hard to remove the old sensor from the block and using channel lock pliers was awkward due to the space limitations. I used a small flat bladed screwdriver, like the one you would carry in your shirt pocket, and slowly worked it between the sensor flange and the block. The sensor released and actually fell on the floor. I agree it is a good idea to replace the connector on the new sensor before installing since the green button on the connector must be returned to the locked position. I used the same small screwdriver to push the green button back into the locked position. I am not a mechanic; but using these instructions, I completed this in about one hour.