RX - 2nd Gen (2004-2009) Discussion topics related to the 2004 -2009 RX330, RX350 and RX400H models

Constant Low Coolant Gauge

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Old 01-21-20, 02:02 AM
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crz95
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Default Constant Low Coolant Gauge

Hello,

Might be a noob question as I'm new to Lexus ownership. (2005 RX 330)

I've noticed that the car's temperature has never been exactly in the middle of Hot and Cold, like every other car I've owned. It's always a dash under middle. Ignored that all summer as I thought that was normal.

Yesterday drove down from the mountains and the temp was just 1 dash over Cold the whole way down. Never experienced that in any car I've previously owned. Outside temp. was 3-10 degrees celsius (37-50 F) during the trip.

Is this normal? Or could my temperature sensor be dirty or stuck open? Check attached image.

Thanks!


Last edited by crz95; 01-21-20 at 02:04 AM. Reason: forgot to add attachment
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Margate330 (01-21-20)
Old 01-21-20, 02:08 AM
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crz95
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Forgot to add: The car takes a considerable amount of time to warm up every morning. I usually wait for the RPM to go down from 1.5k to 600 before I take off. Takes less than a minute in my other cars but over 3 minutes in the Lexus. This might be related
Old 01-21-20, 03:07 AM
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EastTNLex
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It could be your thermostat is starting to/is failing.
Old 01-21-20, 04:00 AM
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Mesquite77
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Wow, a 2005 with only 41K! I agree with EastTNLex, your thermostat is stuck open, from not being used enough, lol.
Old 01-21-20, 04:35 AM
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mandyfig
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Try purging, you might have air in your system. Any work done on the RX that would have required a coolant drain? Otherwise your thermostat needs replacement.
Old 01-21-20, 05:10 AM
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crz95
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Originally Posted by Mesquite77
Wow, a 2005 with only 41K! I agree with EastTNLex, your thermostat is stuck open, from not being used enough, lol.
Yes! It's Kilometers too. Bought it this August with 33K. Single owner, older man that wouldn't drive it at all. The dealership confirmed that it's the lowest milage 2nd gen RX in my country
Old 01-21-20, 05:11 AM
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crz95
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Originally Posted by mandyfig
Try purging, you might have air in your system. Any work done on the RX that would have required a coolant drain? Otherwise your thermostat needs replacement.
Thanks for your reply. Not to my knowledge, I've only had the timing belt done in summer. Just booked an appointment for Friday, research shows that it's most probably the thermostat.
Old 01-21-20, 05:12 AM
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Margate330
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My 2004 RX330 normal operating temp is runs exactly on the 2nd line above cold.
According to my scanner this is at my Thermostat temp of 190 F degrees exactly and takes a couple mins to get there.
PS- The 3rd line above cold is over boiling temp as verified by my scanner one time when I got a little hot and this is never good so If you see this plz pull over and get help.
* Suspect possible Tstat like others but if not it needs it anyway if original.
Congrats for having a 40k mile RX330.
Old 01-21-20, 05:15 AM
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crz95
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Originally Posted by Margate330
My 2004 RX330 normal operating temp is runs exactly on the 2nd line above cold.
According to my scanner this is at my Thermostat temp of 190 F degrees exactly and takes a couple mins to get there.
PS- The 3rd line above cold is over boiling temp as verified by my scanner one time when I got a little hot and this is never good so If you see this plz pull over and get help.
* Suspect possible Tstat like others but if not it needs it anyway if original.
Congrats for having a 40k mile RX330.
Thank you!
So I guess this is normal then?
Can't tell you how many people have tried buying it from me.
Old 01-21-20, 05:29 AM
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Margate330
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Originally Posted by crz95
So I guess this is normal then?
If you are running on the 2nd line above cold this is normal- 3 lines above is danger.
But at 40-50f on colder days you should still be on the 2nd line if the thermostat is working.
So I would suspect faulty thermostat and the cooling system checked out for problems to be safe as others have posted.
PS- I wouldn't take a chance on a 16yr old tstat.
Old 01-21-20, 05:51 AM
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crz95
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Originally Posted by Margate330
If you are running on the 2nd line above cold this is normal- 3 lines above is danger.
But at 40-50f on colder days you should still be on the 2nd line if the thermostat is working.
So I would suspect faulty thermostat and the cooling system checked out for problems to be safe as others have posted.
PS- I wouldn't take a chance on a 16yr old tstat.

Awesome. Appreciate your help & time. Cheers!
Old 01-21-20, 07:33 AM
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matts6887
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speaking of tstat; Im not sure if mine is original or not; but for the little over 3 years ive had my second gen rx which soon will be no more hopefully because of a rod knock(s); ive never had any overheating issues thankfully. I have had one coolant drain and fill done and its probably due for another along with transmission fluid; but im not gonna bother if im just gonna be going to a 3rd gen rx.
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