My Check Engine Soon light has been coming on every so often for two or three years. After a day or so and several cool down / restart cycles, it has always gone off. To my knowledge, my fuel economy has been pretty consistent at 14 to 15 mpg since I've owned the car.
My alternator died the other day and I had to be towed to a repair shop. They replaced the alt, but the tech reported that he got a CES light and he retrieved codes P1133 and P1406 from the computer.
I was told that P1133 has to do with fuel/air metering (perhaps the O2 sensor?) and that P1406 has to do with auxiliary emission control (perhaps the EGR?).
The car has about 180,000 miles, and still has the original spark plugs.
Can I get some suggestions as to what to do with these intermittent CES codes? And, if I replace the O2 sensor and/or EGR, how do I clear the codes?

1133 means the o2 isnt switching as expected, generally means its wore out. 1406 means egr pintle position, there could be alot of carbon build up but it likely has to be replaced as well. you can only reset codes with a scan tool on cars after 96

I have a 96 gmc suburban that used to get great mileage. ie 23 24 hwy.
oit has since dropped off badly to 14 16.
I replaced the cat and muffler as I was getting a p0420 code but the mileage has not returned. i have also replaced the fuel pump and relay to same.
it has stalled a few times as if it were not geting gas and by cleaning the fuse blaok where the relay plugs in I have gotten it going again but still the mileage is bad.
so Yesterday it flashes the code p1406 egr pintle. I tryed to get a new fuse block but they are no longer available from gm and the ones at the local junk yard looked little better than my own. the code cleared itsself
so i got a set of picks and some contact cleaner and worked on the contacts for the fuel pump relay and it feels like it is running better no codes but I sus[ect I may need to change out the egr.
Is it best to swap or clean the thing and do you guys think that will help clear up the way it runs and bring the mileage back? or am i barking up the wrong tree?
the truck did sit for 6 years while i worked 7 days a week but is now our daily driver again. now that i am out of the work truck. so perhaps this contributed to the corrosion of the fuse block and issues with the egr?
any thought are appreciated.

the fuses are not likely the issue here, egr'* get full of carbon and stick. if they stick open its a big vacuum leak. ive tried cleaning the pintle and spring on a couple cars and it didnt really help they eventually needed replaced

I kinda suspected as much. thank you.

my only concern was the fuel pump relay is not getting good contact from the fuse block and that has caused the stalling issue.
I think i have it fixed now but I have only gone a hundred miles or so since working on it so it is hard to say for sure just yet.
Weird electrical things are not my forte so i thought i would check in and see if anyone else has had strange stuff related to the fuse block.

I will try to get time to pull the egr today and see if just cleaning and checking hoses is enough. i just want to get my mileage back up to amazing it was always one of the things i liked best about the 96 vortex and part of what makes it my favorite year.

I have never heard of anyone getting that kind of mileage. mine was poor but i replaced the pos poppet injectors with the new mpfi, and it went up to as most others get 14 to 15.

i live in the mountains and most if not all my driving is highway and there is just something about the first year vortec before the gov got more involved. mt work truck got 25.6 hand calculated with a 305 (5.0) at 55 but it is hard to keep at 55 it averaged 23.5 and the suburban with a 350 fluctuated between 23 and 24.
even the newer ones regularly get 20 but the 96 does a little better ( and has a more spacious interior, in my opinion) and for that reason it is my favorite year. the suburban USED to go over 700 miles on a full tank but now is down to just under 500 that is a HUGE drop off and I am not sure what to do to fix it.
oh i baby my pedles most of the time too which really helps maximize mileage

only so much you can do driving a brick. i dont drive any highway though, im sure that makes a difference

yea in city driving mileage was always crap. the fuse block was problematic i finally found a mechanic who had run into the same thing twice before and helped me out with it. that seems to have helped some.
BUT i suspect i am going to have to change a number of sensors in order to get everything back to ship shape.
still need an egr and i have to clean the maf internals every so often to get the excess oil from the k&n filter off them probably WAY overdue for new 02 sensors as well...
any other ideas? and thanks for bouncing ideas