My SES light came on yesterday and it is throwing the code P0128. I have looked up the code and it is the thermostat, All the threads I searched don't show how to replace it. Does anyone have pictures showing how it is done? Thanks for your help in advance.

 

Anyone care to help?

 

i haven't changed one on my maxima yet but i've done plenty of thermostats... just follow the upper radiator hose to where it goes into the motor, you should see a couple bolts holding in the the metal peice it's connected to... un bolt it, pull out the thermostat, pop in the new, put the new gasket on, and bot it back up. It's an easy process, you shouldn't have any problems.

 

That is good info, will my computer clear the code once I replace it, or will I need to get it cleared?

 

you'll need to clear the code. just go to your local autozone or advance auto and ask them if they can clear a code for you... it's free...

 

P0128 also pertains to the coolant temp sensor failing as well, fyi:

SELF-DIAGNOSTICS -2003 Nissan Maxima GLE Page 1 of I

Possibie Causes ':-
Malfunction is detected when engine coolant temperature has not risen enough to open thermostat even
though engine has run long enough. Possible causes are:
Thermostat stuck open.
Leakage from sealing portion of thermostat.
0 Defective ECT sensor.
1. Replace thermostat with an OEM replacement. If an incorrect thermostat is used, the MIL may
coma on. Turn ignition on. Select COOLAN TEMPIS in DATA MONITOR mode with scan tool.
If COOLAN TEMPIS is less than 140°F (60°C), go to next step. If COOLAN TEMPIS is above
than 140°F (60°C), allow engine to cool and repeat step.
2. Drive vehicle at a speed of 50-75 MPH for 10 consecutive minutes. If 1st trip DTC is detected, go
to DIAGNOSTIC PROCEDURE. If 1st trip DTC is not detected, system is okay at this time.

Diagnostic Procedure
1. Turn ignition switch OFF. Remove ECT sensor, and place in heated water.
2. Measure resistance between sensor terminals, with water at specified temperatures.
and ENGINE COOLANT TEMPEUTUm SENSOR RESISTANCE table under
DIAGNOSTIC PROCEDURE under DTC PO1 17 OR DTC PO1 18: ENGINE COOLANT
TEMPERATURE SENSOR. If resistance is as specified, test is complete. If resistance is not as
specified, replace ECT sensor.
O 2008 Mitchell Repair Information Co., LLC.

Sorry for the poor copy/paste, Mitchell makes it kinda difficult to spread the information around, but hopefully you can still get the idea.

Just don't want ya going through all the trouble of replacing your thermostat only to find it was your ECT sensor the whole time.

 

Replace temp sensor 1st. Much easier than t-stat. Don't forget to bleed the cooling system should you replace the t-stat.

 

is the engine temp coming up very slowly when you start the car?

 

My temp seems to come up more slowly than usual. Where is my temp sensor if I need to replace that?

 

Of the temperature is coming up slowly it is most likely the thermostat. Not expensive but tough to get to. Look for an FSM link (do a search), directions are in there.

 

do maximas see any gain by putting in a lower temp thermostat? i know some of the older american cars ppl used to run 160 deg vs 180 and got a little btit of performance gain; any relevance here?

 

No, cars are designed to run best with a coolant temperature in the 190-200 range. Cooling the air your car takes in is where the gains are.

BTW, I never noticed any difference between a 160 and a 180 degree thermostat in either my Chevelle, Cutlass or Z/28.

 

OK, I feel like an idiot even asking this question...but where exactly is the radiator drain plug on a 2000 Maxima? I too have a bad thermostat (stuck open - takes a long time to warm up in winter, cools off going down a long hill) that I'm trying to replace. The thermostat looks easy to get at - just remove the upper hose, three bolts. But I can't find the drain plug!

My owner's manual seems to indicate the drain plug is on the bottom of the radiator - ? Clearly it's nowhere I can reach from above. Do I need to remove a baffle from the front bumper to reach it from below? I was hoping not to have to remove anything from the bumper. I could always remove the big hose directly from the radiator, but I don't want to get anti-freeze all over below...

Thanks!

 

you shouldn't have to drain the radiator I will tell you on my 2000 SE the thermostat and the housing is all one piece. so like some else said follow the upper radiator hose to the engine unhook it and there are three bolts on the housing pull it off and the thermostat will come off with it took me like 30 min. got my new one from autozone for like 20 bucks...

 

they only had one 180 I tried to get a lower temp they didn't have or offer one but again that was autozone..

 

Thanks, I already have the replacement thermostat in its housing and have located the thermostat on the engine. But if I don't drain the coolant from the radiator first and just unhook the hose from engine block, isn't coolant going to come pouring out of the hose and out of the engine block? I'd like to drain it anyway (time to flush it) but I would at least like to drain it in a controlled way. I imagine some coolant will still come out of the block even if I drain the radiator but much less should spill out.

 

Drain is above the lower covers - on back side of radiator.

 

Thanks. So just to be clear: if you were going to drain the radiator, would you get under the car - jack it up or up on ramps - and remove those lower covers to get to the drain plug? Because I don't see any way to get to it from above or, without removing those covers, from below. My alternative seems to be to yank the big radiator hose off the bottom of the radiator and drain it that way - but I'd still need to remove one of the covers off the bumper to drain it without making a big mess.

 

OK mission accomplished: radiator drained, thermostat replaced on my 2000 Maxima.

The radiator drain plug is indeed on the BOTTOM of the radiator (not on the back side) - this is what is indicated in the owner's manual not completely clearly. The plug is on the left side (passenger's side) of the radiator. In fact, there's a hole in the bottom cover where you can reach up and unscrew the plastic plug with a big Philips screwdriver (no hand screw). So you can just remove the plug and coolant will drain right through that hole. I tried to be neat and partly removed the cover, bent it back and stuffed a little funnel up there and when I removed the plug mostly avoided a mess when the coolant came out.

The thermostat on a 2000 Maxima is fairly easy to get to. You don't have to remove anything to get to it, though a tensioner for one of the belts sticks up behind one of the three 10mm bolts, making it a little tight to get in there. But I had a tiny 10mm socket and ratchet that just fit enough for me to get in there and loosen it. The other two bolts were easier to reach. None of the bolts was impossibly tight - in fact you could hand loosen them after they were broken loose (that was easiest for me), and they were long enough that they fortunately didn't fall right out after they were completely loose. The old gasket came off intact and none of it was stuck to the mount so fortunately I didn't have to scrape anything off.

The old thermostat was indeed visibly stuck open; it was completely cool when I removed it so should have been closed if working properly.

Getting the new thermostat and gasket in was just a little tricky but not bad (I'm klutzy and I did it - so can you); in order to get the new gasket to stay flush while I put it in (not much room in there to fiddle with the gasket when you are trying to install) I put the top two bolts in as I worked the new thermostat in. They didn't fall out easily anyway, but I still didn't want to risk it; drop one bolt inside the engine (I've done that before) and you are probably screwed if you can't find it. To prevent the two from falling out, I wrapped a rubber band around them around the outside in a sort of pulley fasion. After getting those top two in I stuffed the bottom one in, then tightened all three (not too tightly but tight enough).

The coolant hadn't been changed in a while but didn't look brown or anything - maybe I could have re-used it. I didn't actually flush the coolant from the block like I probably should have - I just replaced the 5 quarts of coolant that came out with new coolant and called it good for today.

I ordered my thermostat from Rock Auto - about $22 delivered. The thermostat comes mounted in the metal housing and also comes with a gasket.