# water temp gauge not working correctly



## xt_out (Jun 23, 2003)

the water temp gauge in my SER stays on cold and doesnt move anymore. when i first noticed the problem sometimes it would start working again temprarily. it hasnt moved for about 3 days now. im thinking there's a loose connection. could it be the thermostat and would that cause the radiator fans to not work? i haven't checked to see if they go on still. 
what are the possibilities?
could the gauge itself be broken? probably not if it's been working every noiw and then right?


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## Nismo1997 (Dec 26, 2003)

mine did that when i let it sit for 6months..i tapped on it n it was fine..i hope u got the same ez fix as i did..good luck


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## BRSGXE (Sep 19, 2004)

xt_out said:


> the water temp gauge in my SER stays on cold and doesnt move anymore. when i first noticed the problem sometimes it would start working again temprarily. it hasnt moved for about 3 days now. im thinking there's a loose connection. could it be the thermostat and would that cause the radiator fans to not work? i haven't checked to see if they go on still.
> what are the possibilities?
> could the gauge itself be broken? probably not if it's been working every noiw and then right?


First, *check your coolant level*. If coolant level ok, remove the connector
from temp sending unit and ground connector to engine block. Now with
KOEO (Key On Engine Off) look at your temp gauge. If needle moves from
resting spot, gauge is good. Could be one of two things causing a cold 
reading...bad sending unit or a stat stuck open. Taking an ohm reading of
the sending unit before / after engine warm up, will tell you if the unit is
good or not. To see if the stat is tuck open...When engine is cold, open
rad cap and start engine. Look in rad neck and see if there is flow of coolant,
which there shouldn't be since the stat should be closed. Also, could try this.
Start engine and allow to idle for about 10 mins. After 10 mins, shut down
engine then feel upper and lower rad hoses. Upper should be warm/hot to the
touch, lower cool/warm. If both hoses feel about the same, very good
indication of a stat stuck open.


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## xt_out (Jun 23, 2003)

thanks guys. im working 14 hour days for the next week but i'll check that. it continues to work occasionally, and then the next moment, be all the way on cold again.
im sure brsgxe's solution will be the fix.
thank you!


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## Nostrodomas (Jun 15, 2002)

It sounds like the sending unit. If the stat was stuck open it wouldnt just drop to cold.


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## BRSGXE (Sep 19, 2004)

Nostrodomas said:


> It sounds like the sending unit. If the stat was stuck open it wouldnt just drop to cold.


True to some extent. There are 2 factors not taken into consideration and
that is if the situation with the gauge is occuring while the engine is just
idling or while he is doing stop and start driving. If the gauge registers a
reading then drops flat while the car is just idling, then I would just about
say 99.99% of the time it is the sending unit. If the gauges slightly fluctuates
(registers low temp then drops flat) while doing stop and start driving, then
the possibility of a stat stuck open is very good. Nostros, like you I am also
leaning towards the sending unit. :thumbup:


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## Nostrodomas (Jun 15, 2002)

Very true. Lets just hope it isnt the stat. The sending unit is a whole lot less of a headache than the Thermostat.......


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## vini_i (Jul 24, 2004)

here's another idea to think about. when was the last time the coolant system was flushed?

something that people don't realize is that coolant is slightly acidic and with dissimilar metals in the engine it can create a voltage which in tern can short the coolant temperature sensor and cause it to always read cold. 

to check how acidic the coolant is take a volt meter and stick the positive lead in the coolant at the radiator fill neck. then toch the negative lead to a ground. the meter in DC volts should read no more than 0.5 volts if it does change the coolant before doing anything else.


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## BRSGXE (Sep 19, 2004)

ViNi...very good point! A situation I have seen but forgot about having not seen it
happen enough. What you just mentioned, reaked havoc on a friends car years ago.


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## michaelwhk (Oct 14, 2014)

*Mr*

I have the same problem in that the gauge lays flat, but moves up a bit in a few days time. Sometimes its flat even when the engine is hot and the fans running. I removed the thermostat earlier as mechanics suggested not needed for this kind of wheather (Namibia). I doubt its the thermoswitch as the Nissan dealer recently okd electronics including that when it was working. I know the timing is not 100%, but will replace coolant as easiest and cheapest.


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## smj999smj (Jan 1, 2006)

Disconnect the harness connector from the temp switch and ground it. With the key "on," the gauge needle should go to full hot. If it does, the gauge is working and the circuit is good. This means that either your temperature sender is bad or the coolant isn't getting hot enough. Personally, I would install the thermostat. While I can understand the thinking that the hot temps don't require it, there are a couple of problems that can occur. On a computer controlled engine, the engine needs to reach a specified operating temperature in order to enter closed loop, when the ECM will use input from the oxygen sensors and adjust the fuel trim accordingly, so the engine will run more efficiently. The quicker the engine reaches normal operating temperature, the faster it will enter closed loop. If the engine runs too cold, it will also be unable to burn off any condensation that may occur in the crankcase. Whoever told you to run it without a thermostat simply doesn't know what they are talking about.


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## michaelwhk (Oct 14, 2014)

I had the problem fixed. The contact point was loose while still attached so they just used lead to solder it and it works well. Though the thermo needle lies at about 3/4 up just underneath the red. This is after I installed the thermostat back. However the fans kicks in immediately when the car becomes hot, without the needle moving any closer to the danger zone.


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## Beto23 (Nov 3, 2015)

*Pics*

Can someone post pics of the sending unit to the gauge and the sensor itself? There are two different things to check here right??


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## michaelwhk (Oct 14, 2014)

Beto23 said:


> Can someone post pics of the sending unit to the gauge and the sensor itself? There are two different things to check here right??


hi Beto23, I doubt I will be able to post a pic as it is well behind at a dark spot. Yes there are 2 different things to check. If the fan is working you can ignore the thermo switch for now (please come back for if the switch is a problem as well), but if the needle/gauge is not working (showing how hot or cold the engine is), then the problem is the sending unit. In the meantime if I may explain based on my 1998 model Nissan sentra. There is an aluminium/iron pipe just above the oilfilter (on driver's side, right hand driven) and it is attached to the top/cylinder head. On that pipe the fan switch is attached whose tip when installed touches the water as it runs through. It has a plug attached to it with electric wires, which is the thermo switch which you can ignore the, but next to it on the same pipe is the single thin wire with a terminal (I think female) plugged into the pipe. This is the sending unit. The sending unit looks like this https://www.google.com.na/search?q=...=EU7dVu2tHsmAywP_0r24Ag#imgrc=GC2LW9D0w2aB5M:. in the meantime the terminal image is something similar to this 100x Blue Insulated Spade Crimp Wire Cable Connector Terminal Male Female Kit | eBay


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## Motianes (Oct 15, 2016)

Dear sir,
I have a 1998 nissan pathfinder SE automatic transmission. When i crank the car, the temperature gauge moves way up to hot, gas gauge is stuck up at full even when the gas is almost empty, RPM doesn't go above 1000 rpm when accelerated, speedometer doesn't work, automatic gear does change when accelerating. 

Any way forward?


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## G20 (Aug 24, 2009)

Hey guys. 

Was thinking about putting up a new post but seeing that my situation is kinda similiar to this one i thought i'd just ask here.

I have a 2000 Nissan Primera ( G20 US market equivalent ) that has a QG18DE engine in it.

My issue is that my temp gauge goes all the way up to the 3/4 mark and only then does my fan come on. When the car is switched off, it takes forever for the gauge to go back down. I've also checked the car on a diagnostic scanner and the temp reads normal when the engine is running for a while.

I have done the following so far but no change:

1. Changed the Temp Sending Unit
2. Changed the Thermostat
3. Changed the coolant 
4. Checked the wire from the Temp Sending unit to make sure there's no breakage or damage in the wire.

Any suggestions on what else i can check ?

Thanks


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