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lexpert, Lexus Master tech
Category: Lexus
Satisfied Customers: 2100
Experience:  Master Certified with lexus, 8 years experience with Lexus
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My daughter has a 1999 LS 400 wth 90k miles. Recently when

Customer Question

My daughter has a 1999 LS 400 wth 90k miles. Recently when starting the temperature gauge was observed immediately going to the halfway mark. After driving a short time the needle would go up to just under the red area, but it never seemed the engine was
as hot as the gauge indicated. Car was given to a mechanic who changed the thermostat and water pump, however the car is still doing the same thing as far as elevated temperature gauge. I'm going to intervene and try to help her myself. Any ideas? temperature
Submitted: 1 year ago.
Category: Lexus
Expert:  john -aka eauto replied 1 year ago.

is this immediate ?

Customer: replied 1 year ago.
immediate goes up to at least halfway hot at the turn of the key. Also the temp sender was replaced
Expert:  john -aka eauto replied 1 year ago.

do you have a scan tool that reads live sensor data?

Customer: replied 1 year ago.
no but i have acces to one. would i be checking for temperature reading?
Expert:  john -aka eauto replied 1 year ago.

exactly..we need to see what the coolant temp is on start up... it may be a faulty sensor or harness or a faulty cluster

Customer: replied 1 year ago.
i would think at start up it wpould be the same as the ambient air temp. remember the sensor/sender was replaced. are there two? wouldnt faulty harness throw a code?
Expert:  john -aka eauto replied 1 year ago.

ambient air is the air feeding into the throttle body, it should throw a cts circuit code but not always

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