How to Replace the Crankshaft Sensor on a 2005 Nissan Altima

by Alexis Rohlin
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Crankshaft sensors monitor the rotational speed and position of the pistons in relationship to the crankshaft of a car engine. The car's computer uses the information that the crankshaft sensor sends it to control the ignition system timing of the engine. By sensing the position of the pistons in relation to the valves of an engine, the crankshaft sensor helps the car computer maintain the valve timing. When a crankshaft sensor fails, the engine will not time right and will stall out or not start at all.

Step 1

Remove the hex or Allen head bolts and take off the plastic engine cover. Take out the air tube that connects the throttle chamber to the air filter box.

Step 2

Remove the valve cover breather hose and the air tube it is attached to.

Step 3

Set your drop light down under the rubber heater hoses, which are located near the firewall of the driver's side of the vehicle. Shine the light toward the back of the engine block. Below the intake runners on the driver's side you will see a valve cover and the throttle chamber. If you look straight down from the valve cover to the ground, you will see a black wire connected to a sensor that has a green tab on it. That is the crankshaft sensor. It will be secured to the engine block by a gold 10-millimeter hex bolt.

Step 4

The green tab of the sensor is a plastic clip that holds it in place. Push the tab down by using a flat-head screwdriver. Push it down toward the engine while you pull the wire connector with your other hand until the wire connector clicks and pulls away.

Step 5

Place the 6-inch extender on the ratchet and use it to remove the 10-millimeter bolt that secures the crankshaft sensor to the engine mount block. Use the needle nose pliers to grab ahold of the sensor's black housing and pull it out.

Step 6

Take a rag and clean out the connectors on the engine block.

Step 7

Insert the 10-millimeter bolt through the new crankshaft sensor housing and engine block. Use the ratchet to secure it into place. Insert the new crankshaft sensor into the housing. Re-install the black wire housing that connects to the crankshaft sensor until it locks with an audible click. Re-install the air hose and the engine block cover.

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