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Jan Andersson
Jan Andersson, ASE Master Tech
Category: Nissan
Satisfied Customers: 834
Experience:  20 years of automotive repair & modification, USA, Asian, Euro, old & new cars.
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What does an intake air temperature sensor do?

This answer was rated:

what does the intake air temp sensor do and what kind of damage can it do if bad?

The intake air temp sensor monitors the air temperature going into the engine, and sends the data to the engine management computer. The computer then adjusts the fuel mixture to match some pre set target values, using the air temp data as input. The idea is to keep the fuel mixture optimal in all driving conditions and climates. If the temp sensor is bad or is sending wrong signals, the computer will meter the wrong amount of fuel into the engine. It may give it too much fuel causing the engine to run rich. (Carbon deposit build up, possible ignition trouble as the carbon keeps building up, fouled plugs, fouled sensors here and there, poor mileage, faster cylinder wear when fuel washes the oil off the cylinder wall)

It could also adjust the mixture to lean, which would cause detonation/pinging, overheating parts of the engine, poor performance, and in extreme cases mechanical failure like broken or burnt valves and pistons. The intake air temp sensor is generally found in the air cleaner box, or the big pipe/hose leading to the throttle body. Usually it is a small thumb size sensor with 2 wires going to it. I can’t remember or find detailed descriptions on where it is in YOUR vehicle. Sorry.

In other words, it is a critical component used to determine how much fuel is injected into the engine at any given time.

Customer: replied 8 years ago.
do you know ruffly how much this part costs through nissan i have not been able to find it anywhere else also if put in wrong will it read that their is a problem

The intake air temp sensor could also be called Ambient air temperature sensor and it may be elsewhere in the front of the car, not necessarily in the intake air ducting. One of those can be found at Autozone for $40.

After checking a repair manual, I found it for you. The book also says this sensor is not used to control the engine, so I was wrong there, sorry. That’s a bit unusual.

Go here for the location (Front bumper air duct opening) and testing procedure, page EC – 111:

http://boredmder.com/FSM/Nissan/Pathfinder/1997/EC.pdf

You can only connect the wire terminal one way.

Customer: replied 8 years ago.
what will this harm and how much does the part cost?
The Nissan repair manual says it is used for diagnostic purposes, so when it is not working properly, you can't perform complete or reliable computer diagnostics on the vehicle. In itself, it seems like it won't do any harm, just prevent or slow down proper diagnostics if you have another problem later on.

I don't have access to Nissan dealer pricing. Autozone listed this at $40.
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