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Discussion Starter · #1 ·
I have a 2008 1.6L and can't find the Ambient temperature sender. The shop manual says it's in front of the condenser near the bottom but there is nothing there.

The reason I ask is when I first start the car and turn on my OBDII gauge it shows the temperature as accurate. Then will switch to a much lower reading.
 

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Your OBDII gauge parameter would be Air Inlet Temp. I'm assuming?. This value is measured using the MAP/ MAT sensor in the inlet manifold, it's showing you the air temperature value that the ECM is using to calculate injector Pulse Width for stuff like cold start enrichment, how much idle correction to dial in for power steering loads, etc. When you first start your car it's normal for connected OBD devices to briefly use and display the last 'good' data they received until they have time to catch the new data packets flowing on the Canbus. The sensor you are referring to on the upright near the middle of the condenser is part of the 'full climate control' A/C system with the fancy 'Auto' button, base models with the twisty knob A/C don't get that sensor. Cheers
 

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Discussion Starter · #3 ·
There is no air inlet temp sensor. It is the ambient temp sensor and Hyundai tech info shows it in front bottom of the condenser on the drivers side. The IAT sesor in the MAP sensor shows a different reading and is not the same.


Just wonder why I get a good reading and then it goes to a colder reading and stays there.
 

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Ambient Air Temp out at front of car IS NOT an input to OBD-II.. it is used for HVAC

Air temp for OBD-II is the Intake Air Temp sensor on the MAF or MAP (depending on which method used for air flow measure)..
 

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Discussion Starter · #6 ·
I just went out and connected my Torque App to it. It shows the ambient air temp as an OBDII input and when I started the car up it does show an accurate number and does not follow the IAT.

Not saying it's a normal OBDII input but most OBDII systems have an ambient air temp sensor. At least the last two other cars I've had since 1997 do. I'll see tonight if the temp stays accurate withe Torque app.
 

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Some OBD systems have another sensor up in the air filter housing or inlet duct, that one is used on cars for air volume calculation corrections, the airflow through the throttle body can be calculated more accurately if temperature and therefore density is known. Tends to be fitted to high performance large capacity engines. (LS1's etc).

A bit of a trap with OBD is that it is an industry standard which caters for over two hundred different sensors alone. When you plug in your reader and start the car, the ECM starts sending messages down the Canbus in 'packets', think of an envelope. On the outside of each envelope is an industry identifier number, for example, envelope 1 always has info on say RPM (it isn't but for example here). Now you have set up your reader to display water temperature, rpm and a few other items, the reader watches the envelopes go past until it sees envelope 1, I need that one it says and removes it from the data flow, it then sees envelope 27 (the water temp packet for example) that it needs for water temp, it grabs that one as well. This is happening thousands of times a second. Then to confuse the issue Hyundai add in extra non standard packets for their own use. In summary all readers will have parameters that Hyundai don't provide packets for. Hyundai provide packets that only some readers will be able to understand. It's a great system, but with limitations.
 
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