Wouldn't hurt to have one. But, make sure it can read data. The MT2500s (snap on) are getting cheaper these days, and can also do OBDII. Quite a useful tool to have in the garage.

Got a volt meter? Might be able to test the sensor that way.......

 

I've been looking into a Matco one. Yes I do have a dmm

 

See if you are getting 5 volts TO the sensor, and see what voltage is coming out of the sensor.

 

Where is the sensor located that I am testing?

 

Just to the drivers side of the thermostat housing. Two wire sensor. Pain in the keester to get to......

 

Okay thanks. Is there anything else's that would cause that? I'm out of town at the moment with some free time. Just trying to figure out where to go with the truck. When I get back.

 

Temp sensor is the most likely culprit. Aside from that, leaking fuel injectors? If all of them are fuel fouled, I doubt the injectors are the issue.

 

Okay thank you. Yeah they all are fouled. I wasn't thinking injectors either

 

Okay I tested the sensor. It was good. I also tested for 5volts and the ground. They were both good

 

Oh, 95...... I need to pay more attention.

May want to have a look at your EGR system as well.

I would still like to see live data for the temp sensor. That seems to be the most likely cause, but, if it isn't.... time to go digging deeper.

Also: How old is your O2 sensor? Wonder if it is just getting old, and slow, and lying to the PCM..... Not like the PCM would know if it was.... (so, won't necessarily set a code.)