I was pulling my camper with my 2005 f150 5.4, I went to pass a slower car all was going well till the emissions warning light came on and the truck felt like it loss all power. I limped it home and tried checking it for code with my hand held but no codes were found. It is running fine no bad sounds or anything noticeablely wrong, just the light on and no power. Anyone have any ideas? Oh, it is lifted 6" and has 35" tires with cat back exhaust with 40K on it. Thanks

 

I would guess O2 sensor.

 

It sounds like it went into limp home mode. When the ECM detects a failure, such as overheating etc, it puts the engine in limp mode. It could be a faulty sensor to an upgrade to the middleware code in the ECM. Take it to the dealer.

 

as kevinM stated.....your truck defidnetly went limp on you..........take her to the dealer and get it straightened out again...sensors would be the most likley curperate....

 

not sure how NO POWER = RUNNING FINE

 

An O2 sensor cannot cause this.

Time for a better scan tool.....

Steve

 

I doubt it's an 02. It would have just thrown it in limp mode and ran really rich but would still have power. My guess is a clogged cat or something of that nature..

 

Bad temp sensor telling the PCM that it is over heating will put it in limp mode, and deactivate cylinders. It's a built in protection Ford has in their vehicles. I agree a bad O2 sensor will post a CEL (check engine light) along with a code and proabably run rich. The mode is known a Failure Mode Effects Management (FMEM). The PCM substitutes a working value if a sensor fails

It could have also been a miss fire, which will cause the CEL to activate.

 

sounds like you overheated or your temp sensor failed. the motor went failsafe. you probably did overheat a little bit.

is the truck running fine now? if the problem is persistent, then that makes me think your temp sensor has failed. that, or the PCM needs to be reset after a limp mode is actuated.

 

I had a friend with a BETTER scan tool check for codes and it came up with 3 codes.

1. 02 sensor bank 1 lean
2. fuel pressure regulator sensor low pressure
3. random misfire cylinder 1

I think the engine was starving for fuel since that would explain all 3 codes above. So, maybe a clog fuel filter??? I going to change it out in the morning.

 

We have had a crap load of F150 fuel pumps going bad this past few weeks... dozens of them.

 

So it could have been an O2 then....Well

 

O2 sensor went lean due to fuel pressure low or missfire