alright, so I have an issue with my 96 D1, this morning after getting gas on my waay to work it started to hesitate and backfire, when I left work for a short while it was fine then it started doing it again. Used my UG to check the 02 sensors and my b1s1 is showing a constant 1.265ish volts, and my short term trim will stay at 22.44, when it sits for a while it will return to normal but goes back to with the 02 going back and forth and fuel trims looking fine, eventually goes back up, although it doesnt hesitate...also my b1s2 is dead currently, could faulty 02s be my issue?

 

OK, just to get started on the correct foot let's take some of the doubt out of the orientation of the O2's...

By "b1s1" I'm going to assume you mean 'bank 1, upstream'

By "b1s2" I'm going to assume you mean 'bank 1, downstream'

The downstream O2's just make sure the upstreams are working, the data they feed the ECU is not actually used to adjust fuel trim.

The upstream O2s are critical and the over-fueling (large positive fuel trim) could be something as simple as a bad plug and/or wire causing a situation where on (or more) cylinders are not achieving combustion. The raw fuel is sent through the exhaust and the O2 reads that as a large positive fuel trim. I'd start there.

8mm Kingsborne wires seem to work well for me and many others here...
Spark Plug Wires for Defender, Discovery and Range Rover

And cheap plugs such as copper Champions or NGK BPR6ES (I use the NGK's)

Let us know how it goes.

Also, it is always helpful for the casual reader to see what truck you have in your signature line. Consider adding that by clicking in the "USER CP" section.

 

plugs and wires are newish, both NGK, today after driving back from work I didnt have any hesitation or sputtering, but my 02 readings where the same. When restarting it goes back to normal for alittle bit but then the high 02 voltage and short term trim goes back up.

 

If the O2 sensor is constant that would suggest to me that it is dead. Swap with the other side to see if the 'problem' follows.

If you need them I've been told, but don't know this to be a fact, that it is best to change both upstreams at the same time.

I suspect your truck is non-AEL but you should confirm by looking at the canister in the engine compartment. Round is non-AEL and rectangle is AEL. Different O2 sensors.

https://landroverforums.com/forum/di...02/#post567770

 

So another p1138 code popped up, I changed the fuel filter, it was nasty. but I notice I get normal readings after a restart(cold or hot) for about 5-6 mins of driving then bank 1 02 stays at the 1.2 voltage, it will drop down when Im cruising and I let off the throttle but goes right back up, doesnt matter if at idle or not.

 

It's non-AEL, it's a 96 Walt.

P1138 is the downstream sensor on the driver's side...... so what. What other codes is it tossing out that you didn't mention....?

 

thats the only one, not pendings either.

 

Well remove the four spark plugs on the drivers side and compare them, checking combustion for over-fueling like a sticking injector, a spark grounding at the coil..... that sort of thing.