Outside temperature wrong - faulty sensor or what?

My experience has been that if the sensor is wet (such as out of a carwash), it will read low for an extended period of time.

 

My problem (well not really a problem) is that the sesor sometimes under the sun will read higher temperature than what it should be.

So if the temp is supposed to be 24c then it can read up to 28-30c under the sun.

Otherwise I believe it is very accurate especially in the winter. It always reads what the weather channels says what it should be.

 

Patrick Wong has indicated that the temperature sensor is located behind the front grill in front of the radiator, more on the driver's side.

Other than for about 10 minutes after going through a car wash, my temperature indication seems to be very accurate.

I would think that unless you find moisture or other foreign matter on the sensor, then it would be a defective sensor.

 

I know GM cars have a number of criteria, and I assume Toyota does as well, that must be met before the temperature will be sampled and the display updated. This is to prevent inaccurate temps from being displayed due to radiated engine/radiator heat. The vehicle must have been moving a minimum speed for a minimum period of time. One extreme is sitting still, where it would not update at all, and the other extreme is at high speeds where no radiated heat can reach the sensor, which is in front of the radiator.

I've also noticed that coming out of my relatively cool garage on a hot day takes a surprising amount of time for the sensor to warm up to the OAT, as in a number of miles.

 

Not much to add other then I have the same problem - it takes long to start registering the correct outdoor temp.
Our other (a 2002 Nissan) has the same problem.
Danny

 

I just started having this problem today when I left garage it was on 84 F and outside was 98 F it took 10 minutes and moved up 2 degrees and then it seemed it moved in 2 degreee increments every 3 or 4 minutes and got to correct outside temp in about 1/2 hour. The car was completely dry as was the outside weather. After working properly for almost 2 years, this just started. Defective sensor?

 

my brand new pip is exactly like that. my 08 was slow, but you could watch the rise after a few minutes. now, it's at least a half hour and i'm not sure it ever reaches the actual temp.

 

Sometimes my temperature is correct and sometimes it does not change after I leave the cooler garage on my 11 Prius. My 03 Camry and 04 Sienna van have gotten slower to change or not change at all as they have aged. Of course, if I take the Prius to the dealer it will work while it is there.

 

goes without saying.

 

Happened to me today. The car was sitting in the sun after my 30,000 mile service. Outside temp 91F. I get in the car. Outside reading 79F. I drive a mile. Never changes. Bring it back to dealer to have him look at it. It takes him 75 mins to finally get to it. By that time, the temperature is reading 90F so "everything must be fine now." I leave; drive 15 miles. Temperature drops from 90F to 88F. Outside temp is actually 84F. Believable. 2 hours later, I get in car. Outside temp reads 88F (still). After about another 10mins, temp drops to 86F. Outside temp is 84F, late in the day. So, I guess it could be functioning correctly. I am waiting to see what it looks like tomorrow morning. Hate to waste my time at the dealer again.

 

sounds like mine, just takes forever to get up to speed. i can't really understand why. it's as if the sensor is too isolated or something. first time in 6 toyota's that i've seen it. i wonder if toyota has a spec on how quickly it sould react. mine can take 10-15 miles/half an hour to reach the correct temp.

 

Same way here...and sometimes even longer.

 

I had a case of "stuck" temperature reading on my 2005. It took disconnecting and re-connecting the plug several times to restore a good contact to fix it. The sensor/connector is in front of the radiator, in the middle of grille as far as I remember. It's exposed to all kinds of ambient conditions so its not surprising the contact can get bad over time.

Thanks,
- Alex

 

Except I have 7k miles on mine and it has been way off since the start.

 

mine also, 2000 miles, new 04-20-12. mayybe disconnecting and reconnecting would help tho. i wonder if it's in the grille on the gen III?

 

I am guessing that the sensor readings are sent through a buffer so that sudden changes don't disrupt the current reading. Otherwise if there wasn't any damping of the reading, each slight change in temp would show up right away and the readout would never be constant. A similar set up exists for the fuel gauge reading so that when the fuel sloshes around your indication doesn't follow suit.

 

agreed, but this is my 7th toyota and it's never been this slow. when i leave my 75 degree garage, i would like to know that it's 90 outside within a few minutes/miles.