P0119 Intermittent Temp Sensor Weird problem

[Chris Galbraith]

So before everyone says "it is the temp sensor". I had a mechanic replace the sensor but the code came back so he replaced it with a Ford sensor and new leads. The problem went away for about 2 weeks and then came back. I cleared the code but it came back in another 2-3 weeks. The mechanic tried chasing down a wiring problem but everything checked out. The truck runs fine with the error code so I have just lived with it. Problems is at registration time, with the error code the truck will not pass "emissions" certification. Sometimes the code disappears for a few days and then comes back.
The mechanic wonders if it might be the PCM(computer). Any thoughts?

 

[John Stephan]

It could also be a bad wire in the harness. Its possible that the tech checked wire integrity when then engine wasn't running and the wire is in a static position, therefore has good connection. When you hit a bump or torque the engine, things move. You'd need test and jiggle the harness to find that the wire is broken somewhere. If you have Torque Pro, you can graph the sensor output and be able to see when it cuts out and comes back. If you don't have Torque Pro, I highly recommend it.

 

[1955moose]

What year and engine please?

Sent from my N9131 using Tapatalk

 

[Chris Galbraith]

2005 Expedition XLT 5.4L 3V