Temp Needle variations

[Mirkz]

Hi everyone,

My temp needle over the past 2-3 weeks has started acting strangely so I'm just trying to diagnose the issue before throwing money at things for no real reason.

Sometimes I've noticed the needle gauge will only move up slightly once it's at full running temp. Usually it sits just a bit below half on the gauge. Sometimes I've seen it sit at the quarter mark etc.

Today I noticed it started and went to the right temp, then a little bit down the road I noticed it had moved lower down.

I also noted that at one point it it was sitting nearly on dead cold after I had been driving around.

Today is the worst it's been, I'm just wondering if anyone else has experienced this and what the fix was?

 

[wrx884]

did u check the coolent temp while it was doing it man 2 see if it was fluctuating also? hopefully its not a possible head gasket.

 

[Mirkz]

Ah you mean with the hidden menu thing?
didn't check that no.

 

[TonyJZX]

yeah get an exact temp.

my car works fine and i still use the exact temp to get a reading these days

 

[Mirkz]

Okay used the hidden menu tonight and it seemed to change around with the needle.

It seemed to fluctuate from around 84-87 then drop suddenly to about 77, then at a set of lights even dropped to about 71-70. The needle fluctuated quite severely when this occurred.
Then it would go back to 84+.
Later on in the night it was sitting a bit over 90.
Didn't seem steady much at all.

Not sure if it's a temp sensor acting up or something worse :/
any ideas?

 

[justbad4you]

do an error code check as well

Okay used the hidden menu tonight and it seemed to change around with the needle.

It seemed to fluctuate from around 84-87 then drop suddenly to about 77, then at a set of lights even dropped to about 71-70. The needle fluctuated quite severely when this occurred.
Then it would go back to 84+.
Later on in the night it was sitting a bit over 90.
Didn't seem steady much at all.

Not sure if it's a temp sensor acting up or something worse :/
any ideas?

 

[Mirkz]

there's no codes being thrown up, at least no dash lights have been coming on to indicate anything, unless it still logs them without it.

 

[Mirkz]

Just checked it actually and there's a few errors being shown.

16 - Coolant Temp Sensor (Voltage Unstable)

35 Idle speed error (IAC valve unable to control idle speed)

36 Vacuum leak

what's the method to fix all these hahahahaha

 

[Brett_jjj]

First up,disconnect the negative battery termianl for a minute or two,this will clear these error codes from the ECU,after youve reconnected the battery again,check for error codes again to make sure they have cleared properly and that you only get code 12,(code 12=no logged errors),then after driving the car for half an hour or so,recheck the codes again to see if they have returned.If they have returned,this will confirm that theres definitely a problem.Sometimes codes can set because of a one off "Glitch" in the system,so always clear the codes,drive the car,and recheck the codes again...For code 16,check the wires and connectors that go to the sensor.If theres no obvious problem,then replace the sensor,they wear out just like any other part..With code 36,check all the vacuum lines around the engine etc to make sure theres no splits or cracks etc,or undone vacuum hoses.Theres also a vacuum reserve bottle somewhere.On the VS its under the left front guard in behind the bumper.Im not exactly sure where it is on the VT,it might be in the same place,but make sure its vacuum hoses are connected, and that the vacuum reserve bottle is not broken anywhere.With code 35,check the wires and connectors going to the IAC,if theres no obvious problem with the wiring,then renew the IAC valve.Also when replacing any sensors etc,its best to use genuine holden parts,the cheaper ones can cause problems and poor running,and dont last as long.The genuine parts can be more expensive,but its worth it in the long run.If the codes dont come back after the half hour of driving,then recheck them for a few days after to make sure it hasnt returned later on.

 

[Mirkz]

Cheers Brett.
I'd probably say the temp sensor is probably shat itself or there is issues with the wiring considering the temp gauge and digital readout for temp fluctuates.

The IAC I will check over as recently installed a new TB and I may not have plugged it back in properly or something.

The vacuum I've got no idea, did notice a line that was connected to the TB and the rocker cover that had a crack in it, so not sure if that's what's causing the vacuum leak.
Was only a fairly small crack