How to change ECT(Engine Coolant Temperature Sensor) 2003 Pathfinder

[dannocera]

Hello

New to the forum and I've been having problems with my 2003 Nissan Pathfinder starting when it's warmed up.
180K Miles

I've traced the problem to the Engine Coolant Temperature sensor. When the car is warmed up and I shut it off. If I immediately try to restart it cranks but won't start. Also when this condition occurs I noticed the temperature gauge which should read about half way, reads nothing. If I just wait about 3-5 mins when I turn the key and see the temperature gauge reading properly in the middle it will start immediately. If I turn the key and the temp gauge reads nothing then the car will crank and crank but not start. I've also tried unplugging the blue connector to the ECT and the car will start when warm but runs poorly.

How do I replace the ECT? Do I have to take off all the vacuum hoses and the intake manifold to get to the damn sensor at the back of the engine? Why did they put the thing back there!?! Do I have to take both the upper and lower manifold off? Do I also have to take off the fuel injector rails? There's like 20 bolts.

What section of the service manual describes this procedure?

I am so close to fixing this thing but I am worried about basically taking the entire top of the engine off.

How hard of a job is it?

What gaskets will I need to replace?

Thank You!!

[04pathse]

Just wondering if you are getting a check engine / ses light and if so what codes are coming up.

If the ECT is faulty you should be getting an P0117 or P0118 code.

There is some info about the ECT here, doesn't go into what is involved to remove / replace though.

Pages 236-240

http://www.nicoclub.com/FSM/Pathfinder/ ... der/ec.pdf

[Buzzman]

When I had idling problems a few years ago, I thought it might be the ECT sensor.
It turned out to be the dreaded IACV and ECM failure instead. I even bought a new ECT at the time, as a precaution.
I took one look at where it was, and passed on replacing it until I was absolutely sure I had to.
It's in a ridiculous location, down behind the engine at the firewall.
I didn't replace it, and hope I never have to.
Make 100% sure that the sensor is actually your problem.

[rgk]

I believe this car has a coolant temp sensor, which sends the coolant temp info to the ECM, and a coolant temp sender, which sends it to your dash gauge. So if your gauge is reading incorrectly, then your sensor might be fine.

You can check it without having to remove the plenum or even get to the sensor. Check the FSM under the CTS diagnostic trouble code (P0117, P0118): it will show you how to read the resistance values of the sensor by way of a connector.

If I remember correctly, the connector is on the passenger side, tucked under and behind the oxygen sensor connectors. You can get to it without having to take anything apart, and it will give you the voltage and resistance readings for the sensor itself.

If the sensor is indeed bad, your best bet is to find the 'power valve screws' thread here and follow the tutorial for how to remove the plenum. The Haynes repair manual also has a great step-by-step. It's really not that hard once you get the hang of it once or twice.

Once you remove the upper and lower plenums, you're just a 19mm deep socket away from removing that bad boy. Really a pretty easy job, you just have to take your time and do everything in order.