I had a P0171 "system too lean - bank 1" code that I cleared from the computer, drove 100 miles and had another service engine soon light come on. That code was P0174 "system too lean - bank 2". I just cleared it from computer memory and drove around 30 miles with no warning yet. Is this a precursor to needing a new MAF sensor?

 

Possibly, but could have something to do with fouled O2 sensors.

 

How many miles on your truck?
If you get a 3rd. code for a 3rd. or 4th. gear tranny code then you will need a MAF, untill then, don't throw parts at it till you get some more codes.
Mike

 

Thanks Mike. I have 108,000 miles on the truck. I just flushed the tranny fluid, along with the brake fluid, and also replaced left rear hub due to bad seal leaking grease. New plugs and wires at 90,000 miles. Oil and filter are always changed when the odometer hits 3's, 6's, and 9's so never to exceed app. 3350 miles on the oil.

If I had fouled O2 sensors, wouldn't I get a code for the O2 sensors?

 

By mileage, 02 sensors would improve your MPG and power, but not necessarily fix your issue.
With the codes you are getting, I don't know where to point you.
Mike

 

Thanks Mike,
My mileage ranges from slightly under to slightly over 16 mpg (80 to 90% of my driving is highway), and I'm confident that power is not compromised.
The current list of codes I'm getting:
P0171 - system too lean (bank 1)
P0174 - system too lean (bank 2) 100 miles after clearing previous code from computer
P0171 again - 55 miles after clearing previous code from computer
P0174 again - 30 miles after clearing previous code from computer

So I have cleared the most recent code from the computer and will drive it again to se what happens next. Nothing is happening performance-wise to discourage me from driving the truck.........yet (knocking on wood right now). I'll report back after a few more test runs to see if the trend continues.
Thanks again,
Dave

 

It's a sort of rule of thumb anyway to change out your O2's at 100,000 miles. At this point they are probably not reading at optimum levels. Just a thought you may want to consider.

 

Are we talking O2's before CAT or after CAT or both? I'm getting same codes. Counter guy said to be sure to use 92 octane and reset the code. It came back within 20 miles. No other symptoms.

 

It should say Bank one sensor one (before cat) Bank one senson
2 would be after cat.

 

On Disco I's the O2 sensors are due at 82,500 miles.
All of them and at $120 each.