The past two Friday's I have towed a 18' 3 Horse Slant Steel Trailer with only one horse in it about 120 miles roundtrip. On my way home pulling up the same hill, the check engine light has came on. Not a big hill, but at the point I have to step on the pedal to force the downshift in order to maintain the speed limit of 70, the light pops on.

Last Friday I had the code scanned, it was O2 Sensor, so I unhooked the negative battery cable, waited 5 minutes and rehooked. Code did not return until this Friday, I even drove 750 miles for a work trip earlier this week, no trailer in tow though. This Friday, the light went off on its own after a couple of starts and stops I had to make before returning home.

Has anyone else experienced this? or do you think it is just a faulty sensor?

 

What was the exact "P" code number? "O2 sensor" doesn't tell us anything, and I'm betting that there's nothing wrong with the sensor.

What year and engine is this truck?

 

Not sure on the exact code, stopped by Autozone, I think it was bank 2.

09 FX4 Super Crew
5.4

I don't think there is anything wrong either, but I don't think it should be popping on and off just because I pulled a trailer up a hill.

 

You need the exact code number, with out it everything is just a guess.

 

We don't care what Autozone tells you the problem is - we HAVE to have the P-number.