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Amedee
Amedee, Dodge Technician
Category: Dodge
Satisfied Customers: 24744
Experience:  ASE certified tech advanced level specialist. Wisconsin certified emissions state inspector
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2004 Dodge ram 1500: im working..I replaced the air temp sensor

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i'm working on a 2004 Dodge ram 1500. Had code p0073. I replaced the air temp sensor. Same code comes back even before the truck is run.
Hello!

If the air temp sensor that you replaced is good, then chance are you have a wiring issue. Check for a reference voltage to the sensor with the key on.

Sometimes these connectors don't make very good contact and the fix is just to replace the connector itself.
Amedee and 6 other Dodge Specialists are ready to help you
Customer: replied 6 years ago.
Hi, The ref. wire had the normal 5 volts but the other wire also had voltage, it read 2.3. Roy
Did you check it with the sensor plugged in?
Customer: replied 6 years ago.
No I didn't. Should I have? Roy
No... do you have access to a scanner?
Customer: replied 6 years ago.
Yes, I do. I can clear the code and it returns when the switch is turned back on even without cranking the engine.
With the sensor all connected, turn the key on and read the ambient air temp voltage.

Let me know!
Customer: replied 6 years ago.
Ok, I'll do that tomorrow. The customer has taken the truck back home for the night. In the meantime. I'll go ahead and accept this answer and I'll let you know tomorrow the reading with the the sensor connected. Roy
Sounds good!

Let me know!
Customer: replied 6 years ago.
Hi Amedee, Connected ign. on engine not running hot is 56.8 mv. Engine cold not running it is 3.8 mv. Roy

Are you looking at the reading through a scanner?

 

Did you say 56.8 mili volts?

Customer: replied 6 years ago.

That's right.

also I forgot to tell you this truck has a K&N filter system on it. The nipple is so long where the sensor goes in that it is not going to be in the air flow which may be a problem as far as working properly but since the code sets again after a few seconds without even starting the engine there must ba a circuit problem too. Roy

Customer: replied 6 years ago.
I forgot to tell you this truck has a K&N filter system on it. The nipple is so long where the sensor goes in that it is not going to be in the air flow which may be a problem as far as working properly but since the code sets again after a few seconds without even starting the engine there must ba a circuit problem too. Roy
Customer: replied 6 years ago.
Amedee, I just checked again the engine has cooled for 10 minutes and it is reading 4.3 mv. Roy
Well, use a violtmeter and check the voltage out put of the sensor and see if its macthes the scan tool. You will have to backprobe the sensor connector leaving it plugged in.
Customer: replied 6 years ago.
I was using a voltmeter to get these readings. Should I have been using the scan tool? I'll check it with the scanner to see if it matches.

Well, it should not matter what you use. But either way the readings should match.

 

Let me know what you get!

Customer: replied 6 years ago.
Hi, I just checked and found that unplugged the reference wire has 5.01 V. Plug it in the sensor and it has 3.544V. Does that sound like a bad computer ground? Roy
Well, depending on the tempature the sensor is reading, the output voltage will vary. Just be sure that you are on the signal wire that goes back into the computer from the sensor. If so, then I would say that this in normal.
Customer: replied 6 years ago.
I think I made that about as clear as mud. I meant that the voltage on the ref. wire is 5v unplugged and it dropped to 3 1/2 when plugged in. Both measurements on the ref. wire.

Sorry for the confusion. I just want to be sure that we are on the same page.

 

What color wire are you on?

Customer: replied 6 years ago.
It's blue with a green stripe.

Ok. yes... that is the signal wire. This is normal.

 

Now, with it plugged in, look at your scanner intake air temp sensor voltage with the key on and tell me what the voltage reading is.

Customer: replied 6 years ago.
My scanner only gives the temp for some reason it's not showing the volt. for that sensor.

Well, can you try another scanner?

 

What you could do is go to the computer and check input voltage on that wire to be sure its the same reading as the sensor output voltage. Maybe you have got a break in that wire from the temp sensor back to the computer?

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