Trying to find crank sensor

[jravensc]

Hey guys,

i have done a TON of looking online and can't seem to find a straight answer as to where the crankshaft position sensor is located in a 2004 Altima 2.5. If anyone knows or has a diagram I would really appreciate the help.

While I'm here I can give you the back story on this. It is my friends car and he told me a few weeks ago that his car would stall occasionally. Before I could do any research he came back and said the dealership knew about the problem and would fix it. I found out recently that they upgraded his ECU. So cool. Then he tells me that coming back to VA from FL that the car started shaking and the CEL was flashing. So I take the car and run the codes. I get a P0301 or something like that. Misfire detected cylinder 1. Pull the spark plug and its toasted. Replace said spark plug. CEL goes away. 1 week later CEL is back. Check it out again and this time I get the crank sensor. Started looking into this online and have seen a lot of touble with it.(but no location) Yesterday he tells me the car is shaking again. Pull the spark plug. Toasted. In a week it torched the plug. So I am hoping that with the upgraded ECU and a new crank sensor (and now another plug) this problem will be fixed.

[Cold_Zero]

It (crankshaft position sensor) is in the front on the driver's side of the motor. Number 3 on the diagram. It appears you unplug the wires to the sensor and unscrew the bolt that secures the sensor to the block.

Full Diagram

[94GXE]

I beleive the dotted line showng the location of the crank sensor indicates it is located on the rear of the block. It's been a long time since I did any technical drawing though so I could be wrong.

[jravensc]

I just wanted to give you guys a huge thanks. I replaced the sensor today and it was a NIGHTMARE. I consider myself descent at working on cars and I really could not have done it without you guys helping. If I had to 1-10 scale the difficulty I would have to put it at a 7.5.

So the diagram from cold zero got me started and the advice from 94 GXE was spot on. It is located in the back of the motor. And I'm talking about super tough to get at. I had to do the whole thing blind. No visual on the wiring harness(its a push tab..push towards the motor) to the sensor itself. 10mm bolt. You cant get the bolt out with the harness attached so I got that off, got the bolt out, then i had to put the harness back on to get a better grip and remove the sensor. I remind you this is all by feel.

I did want to post this info so others may be able to search it. But i would have to put a disclaimer. Unless their are some tricks to this that I was not aware of, this is a pretty hard job.

So anyway, replaced sensor, has a new spark plug, cleared all CEL codes. Now we wait.

Thanks again,Justin

[jravensc]

An update:

Today I talk to the guy and CEL is back. Took it to zone and this time the code is the infamous P0420. My personal favorite. So now I have to try and determine if the O2 sensor is trash or if the CAT actually went bad. He did drive the car around with a mis-fire. No good. Anybody have a detailed way to determine what the problem is here. I have never tested an O2 sensor. Maybe take it to Nissan and let them tell me? Once again, any advice is appreciated.

J