P0171 (only) code intermittently
 

I’m on the return leg of a road trip and I’m getting a P0171 (Bank 1 too lean) and an occasional rough idle. I reset the code and it usually stays off for a while before popping back on. I can’t do anything about it until I’m back home (500 miles and 2 days). Thoughts as to causes?

Ok, so I’ve had an opportunity to read up more on the code/condition. Basically anything that would cause excess air in to the system after the MAF or anything that prevents the vehicle from delivering the correct amount of fuel could cause the code. Step 1 is to check for vacuum leaks, but I doubt this is the cause because the leak would only have to be pertaining to bank 1 and I don’t think there are any vacuum lines which fit that description (but I’ll check because it’s easy). Step 2is to fix the exhaust leak I have on the bank 1 manifold to down pipe connection. I’ve had this leak for a while and it’s up next on my list to fix anyway, but if air is getting in at the gasket the o2 sensor would see extra oxygen and assume a lean condition and increase the fuel trim to bank 1 (I’m going check fuel trim with my code reader as well).

Which diagnostic tester did you use? A dedicated Land Rover tester is preferred to use on these beasts like a Faultmate, Nanocom, Hawkeye or Foxwell NT510 or NT530.
The only time I've seen a P0171 code is in conjunction with another fault code like P0130: O2 Sensor Circuit Malfunction (Bank 1, Sensor 1).

I read the code through my scangauge (like an ultragauge). I’m going to plug in my “real” tester today and confirm.

As an update to close this out (hopefully): I found that the hard vacuum line that goes in to the top of the throttle body in the far left side was loose, I removed and reseated it, although I don’t know how that would throw a code for just one bank, seems like it would throw a lean code for both banks, but maybe the air flows weird in there.

What I really think solved it was putting some new O2 sensors in. I found a good deal on Rock Auto so figured, why not? It was a fairly easy install, codes went away and fuel economy popped up to boot! I’m pretty sure they haven’t ever been replaced on the truck in it’s entire 175k life based on the built up grime.

I'm chasing the same code. Started when I swapped out the Bosch MAF with a cheapo one. I was chasing a O2 Code (Sonce fixed since I replaced the the O2) switched back to the Bosch and now cant make the code go away. Wondering if I loosened something.

Exhaust leak from manifold to downpipe gave me that code and it cleared up once I put in a new gasket.