I have a 89 2.8, and the SES light comes on intermittantly, so I ran the diagnostic check on it a few times and everytime I come up with a code 25. I have read what it says on this site, but the Chiltons Manual says there is no code 25 for my car, and Autozone's computers agree. One of the guys at Autozone said it was the MAT sensor, it says that could be it on the site, and the chiltons manual has that as code 25 ( but not for my engine and vin). So I figured it was probably that and called the dealer for a MAT sensor (autozone didn't have them). THe guy at the dealer said they didn't have MAT sensors for my car. WTF

Any ideas or suggestions?

 

I belive MAT is same as IAT. And any parts store should carry it.

 

According to my 88 GM Camaro Service manual it says MAT is the Manifold Air Temperature Sensor, which would be IAT just worded differently.

Now I am using the 2.8L code for reference so I could be wrong. The GM Manual says code 25 is the MAT sensor circuit has a high temperature indicated. Code 25 will set if:

- Signal voltage indicated a manifold air temperature greater than 293 degrees Farenheit for 3 seconds.
- Time since engine start is 8 minutes or longer
- A vehicle speed is present

However also it states if you have a short in the tan wire going to the MAT sensor you will get code 25. For reference 185 Ohms is 210 degrees, 450 Ohms is 160 degrees, 1800 Ohms is 100 degrees, 3400 Ohms is 70 degrees, 13,500 Ohms is 20 Degrees. That is if you are going to test the resistance in the circut. Hope that helps.

 

Thanks guys, turns out it was the MAT/IAT sensor, the symptoms seemed to be right on, so I replaced and haven't had a problem since.