4.2 supercharged

Hi all.
I am wondering if anyone can spread some light on my problem.
About a week after I got my l322 the engine light came on and I had to replace all 4 o2 sensors and all has been fine till Saturday when I started the truck the engine light came on again. So I re started the truck and she started but cut out as soon as it started to tick over and did it again on restart but after I reved it she ran nice but engine light was still on.
So I reset ecu by disconnecting the battery and drove 60 miles and no light came on after freezing fishing for a few hours I started her up again to get warm for half hour and still everything was fine till I started her up a few hours later to go home I drove a few hundred feet and engine light came on and now I am getting p0137 and p0134 but all have been replaced 3k ago! Any ideas would be much appreciated

Had similar on my XJ4.2, check there are no air leaks on the inlet side. Also they don't like cheap repo O2 sensors.

You haven't said when the sensors were replaced, so I suppose my question would be, what was the warranty and are they still within it?

Hi thanks for the reply.
I had fitted genuine land rover sensors back in July and I have only done 3k since

Phil90 said:

Hi thanks for the reply.
I had fitted genuine land rover sensors back in July and I have only done 3k since

Click to expand...

Any chance it might be even just one of them at fault? Again, what is the warranty? Is it mileage or time , or one of those x miles or x time depending which comes first? Might be worth looking at?
I'm sure the gurus will have a better answer but checking if they are in warranty isn't a bad thing.

I am sure the sensors are still under warrenty as I only fitted them in July.
Not sure if one has just gone wrong as it is chucking up fault codes for both of them. So I will check for air leaks and go from there unless there would be another reason for it to be causing this fault?

I've seen Bosch fail after 3000miles and a few months.
Even after watching with a graph on a diagnostic reader the behaviour can appear normal but might not be within the ECUs desired parameters..
A front sensor will move up and down with large waves and a rear sensor will move up and down less frequently and with smaller movements and will react to throttle being held open and shut (fully warmed engine).
You can also bench test a lambda by heating the end, it should produce a current, also you should have some resistance from the two black, grey or white wires (depending on the sensor make it model).
They are the heater wires.
Overtightened sensors can fail early as well...