P0128-thermostat
Thread Starter
Joined: Nov 2007
Posts: 4,016
From: Arlington, TX
P0128-thermostat
When I test drove my car before I bought it, the SES light came on. The dealer said he'd take care of it before I picked up the car. When I did, the SES light was off and a paper in the glovebox showed it was a P0138, which is an O2 sensor. Since then, the SES light would come on for a few days, then go off for a few days, then once it got cold a few weeks ago, it came on and stayed on. I figured the dealer just checked the code and reset it.
Anyway, I go by my Dad's mechanic and have him read the code. Turns out all 4 O2 sensors are working perfectly (back two rock steady at .30 so the cat is good). The only stored code was P0128, which is the thermostat. It showed a 171 degree temperature set the code (I believe we have a 180 degree thermostat). I guess it is opening too soon and the engine is running too cool. Probably also why my car takes a good 8-10 miles of driving on cold days to get anywhere near normal operating temperature...and also probably why my mileage has been down about 1-2 mpg when it gets cold.
The thermostat doesn't look too hard to change based on the diagram and directions I got from the mechanic. What is odd though, is no Nissan dealer in the Dallas area has any in stock. He called them all (he can get a better price than I can) and they all told him they'd have to order one and it would be 2-3 days before he'd have it. Is it so abnormal for the thermostat to fail that dealers don't stock them...or is it they fail so often they can't keep them in stock?
Oh yeah, the prices ranged from $22 to $40, with Courtesy Nissan being the highest. Pays to call around!
He reset the code and said he'd call when the thermostat shows up. Anyone have any install tips that would make it easier? The directions I got said the idler pulley needs to be removed and looking with a flashlight, I can't tell for sure if I have enough access to all the bolts with the idler pulley in place. If it has to come off, I minus whale replace both belts, right?
Anyway, I go by my Dad's mechanic and have him read the code. Turns out all 4 O2 sensors are working perfectly (back two rock steady at .30 so the cat is good). The only stored code was P0128, which is the thermostat. It showed a 171 degree temperature set the code (I believe we have a 180 degree thermostat). I guess it is opening too soon and the engine is running too cool. Probably also why my car takes a good 8-10 miles of driving on cold days to get anywhere near normal operating temperature...and also probably why my mileage has been down about 1-2 mpg when it gets cold.
The thermostat doesn't look too hard to change based on the diagram and directions I got from the mechanic. What is odd though, is no Nissan dealer in the Dallas area has any in stock. He called them all (he can get a better price than I can) and they all told him they'd have to order one and it would be 2-3 days before he'd have it. Is it so abnormal for the thermostat to fail that dealers don't stock them...or is it they fail so often they can't keep them in stock?
Oh yeah, the prices ranged from $22 to $40, with Courtesy Nissan being the highest. Pays to call around!
He reset the code and said he'd call when the thermostat shows up. Anyone have any install tips that would make it easier? The directions I got said the idler pulley needs to be removed and looking with a flashlight, I can't tell for sure if I have enough access to all the bolts with the idler pulley in place. If it has to come off, I minus whale replace both belts, right?
Thread Starter
Joined: Nov 2007
Posts: 4,016
From: Arlington, TX
I do have swivel adaptors. I guess since I have to drain the coolant, I'll go ahead and do a flush too. The coolant looks good, but I have no idea when it was last done.
I bought my Z33 unit from Pinnacle for 12$ shipped, a Pathfinder knock off from AutoZone for $19.99. So, yeah it's a toss up. 
Hell, I'd kill to have my ECT steady @ 170*F. As long as you're above 160*F, the ECU is happy (open loop).
Hell, I'd kill to have my ECT steady @ 170*F. As long as you're above 160*F, the ECU is happy (open loop).