Was having hard to start cold or hot with an EGR code 33. Truck sits for a week or two in a cold garage -not used much lately. Fuel is a bit old too so I added a fuel injector treatment. Starting problem cleared by checking/remounting the EGR and replace the EVP sensor which was not in spec. Everything was OK, starting good, then after driving a few times EMISS light came on. Code is 41 during run test only (code 41r = lean, right?). In looking for a vacuum leak as possible cause I checked vacuum to EGR and found none, checked the EGR vacuum solenoid (EVR) and it would not pass vacuum to EGR so replaced it ($41 plus shipping & tax seems high for that part!). EMISS is still on and I can not find any vacuum leaks or anything else to explain it.

Any ideas. Appreciate your help, I'm stumped.

Also, will it hurt to run lean if that is what it really is doing?

 

try cleaning or replacing the o2 sensor, was only way i got rid of code 41

 

By cleaning do you mean to pull the sensor and use a solvent or brush to clean char from the sensor end? Is there a test for the sensor?

 

The EMISS light is operated by a timer and a timer only. The module is under the dash near the accelerator pedal, and can be either reset or unplugged. It is timed to come on every 80000 miles or so to get you to take the truck to the dealer and spend some money.

There really isn't any good way to clean an O2 sensor, but definitely do not use any kind of liquid solvent. The only test is to watch the voltage output from the sensor to see if it is switching between rich and lean like it should.

 

EPNCSU2006 - thanks, I'll check/re-plug the module and let you know if that works. I was under there checking the cruise control brake vacuum swiitch a few weeks ago (unplug-replug the cruise module solved that mysterious problem, but that's another story...). I had no idea about the EMISS light as a maintenance check reminder timer only. IS that written up in more detail anywhere?

b-t-w - does NCSU refer to NC State? My son is an '07 grad.

 

Well, that was it. I spent quite a while under the instrument panel/dash trying to figure out what I was looking for then saw a roughly 3x2 in brown module with a small paper tab with "Reset" written on it, mounted to a metal bracket above and rearword of the gas pedal. Pulled that off and there was the access hole. I used a small straight metal rod to press the reset button hidden inside, first with the key off -but no luck. Then with the key on and still no luck. So I unplugged the module and the EMISS light went off, of course. But I wanted to make sure it was just a reset thing and not some emission fault indicator. So I did a search and found an old thread with the same issue. Someone else had posted the exact reset procedure -I used it and wa-la! EMISS turned off. The procedure that worked: press button first and hold, turn key on, continue hold button pressed 5 sec, release button, EMISS should go off in 2 to 5 seconds.

That was a lot of effort and time for something that Ford could have made simple by putting an emission system check line litem in the maintenance schedule....Anyway, thank you EPNCSU2006 for pointing the way.

 

Glad you got it figured out. I took my truck to the mechanic when the light came on, and when it came back I noticed something unplugged under the dash. I plugged it back in and the light was back on. I think I found the reset procedure in Chilton's manual, but ultimately ended up unplugging the module and moving the wire to the circuit for the Check Engine light so I could wire that to the computer output. I'm not sure why Ford didn't wire the CEL from the factory even though the dash had a spot for it.

NCSU is NC State...I also graduated in '07, a year longer than the 4 years I anticipated when I created the username.