Service engine soon light

Well my engine light come on couple of months ago and I wonder why it come out? So if some one could tell why it come out please

Well am do that too, and im guessing its going to be the transmission but thanks :)

Could a broken or cracked pcv valve/tube cause a PO 171/ PO 174 code to come up? Truck runs like new. We're just really irked over this service engine soon light.

I am a long time certified auto tech and I'm at a dead end.
I have had this same problem for the past year or year and a half. My truck is throwing codes for O2 sensors being too lean. It isn't making sense. I have replaced the upper plenum, MAF twice, DPFE three times, EGR, and both pre-cat O2 sensors twice.
I have checked for vaccuum leaks and post-MAF air leaks. Found nothing.
I am still getting the same symptoms of racing at startup and surging (RPM up and down) at stop lights/signs (mostly when it's cold.
What might the next step be other than taking the truck through the dealership window?

I did use the new port gaskets and isolator bolt assemblies. I'll double check the EGR tube and port, and one other thing I've noticed is that the PCV can get sticky or plugged.I'll give that a shot too.

Thanks

Well, I've checked the EGR ports and tube, was cean.I made sure they were clean when I replaced the EGR valve. But I double checked anyway. The PCV wasn't in the least bit dirty or plugged.
It's still acting up and I'm still at a loss.
One person (wont mention where this person was), suggested flashing the computer. That would be a last resort so I would prefer to try other possible solutions if possible.

I will get those for you. I'm currently at work and will sleep tomorrow during the day, so I won't have a chance to get those codes for a day or 2.

The codes for the first 5 or 6 times were:

P0171 System Too Lean - Bank No. 1.
P0174 System Too Lean - Bank No. 2.

The codes for this last time are:

P1137 Lack of Downstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1.
P1157 Lack of Downstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 2.

I bought a 2002 ford f140 with 92000 miles on it. Today the engine light came on, what can that mean?

Having the computer readout by Autozone says the EGR valve is bad again. I say again because I have replaced it less than a year ago and previously the year earlier.

I have been downsized and so need to do this work myself. Is there something I could have done to to cause the EGR valve to fail or could there be something causing the failure?

Try checking the rest of the DPFE/EGR as you see below:

Had the same problem # 4 in the diagram above, EGR pressure sensor needed to be replaced. Sometimes a little particle gets on it from dirty fuel especially after that many miles, I only had 70k when mine went out. Change it have the service light shut off and see if that works.

Poor gas mileage and check engine light came on.