So my Check Engine light was/is on. I pulled the code and it was P2A00. Take it into the shop because the dealership is responsible for fixing it since I just got it. They hook it up to their scanner and it says o2 Bank 1 sensor 1 range/performance.

The shop replaces both o2 sensors before the cat. I drive it home it is running fine on Tuesday. I drive into work on Wednesday and the light comes back on. I go to Autozone and pull the code and it is the exact same code. I literally watched the mechanic replace both of them. I take it back to the mechanic Wednesday evening. He has it all day yesterday and can't find anything that would be causing the code. He clears it from both computers (his words). Drives it 11 miles and lets it idle for an hour and it won't come back on. I tell him I can't get it until this afternoon and ask him to drive it some more etc.... haven't heard anything yet today.

So I am wondering if you guys have any advice on what it might be? When the guy at autozone put the code in his computer it said it bank 1 o2 sensor, open loop wiring system, and fuel running rich/lean.

So it has 75k miles on it. I ordered new spark plugs and an air filter and will be replacing those on Monday. Can you guys come up with anything else that would be causing this issue to keep coming back. Also where are the o2 sensors before the cat located? I figured they would be in the engine bay but he got up under the truck and replaced them underneath. I am in the process of downloading the rave manual but was hoping maybe someone could steer me in the right direction. The mechanic is stumped and says the undercarriage and the PCM/ECU and everything are in phenomenal shape. The paint is in phenomenal shape minus a couple scratches here and there. The thing seems to have been really well taken care of. Sorry for the novel I am just stumped and so is the mechanic.

 

O2's are located directly infront of and behind the cats.
Replace your plug wires too or else you are just wasting your time.
I dont know about the '05 RR but on the older Land Rovers ('04 and older) 95% of all O2 codes are from the need of a tune up.

Your mechanic sounds like the new type of mechanic that comes out of school these days, they only know what the compute tells them, they know nothing else.
They dont know how to trouble shoot or diagnosis anything, plug it in, read the code, replace "bad" item.
If that does not work replace something else and then keep going until the wallet is empty or the problem is fixed.
Everything "looks" good so they have no idea what to do next.

When spark plugs wear out they do not burn the fuel very well and unburnt fuel gets dumped down stream into the exhaust, the O2's then read a rich mixture and throw a code for a bad O2 because they are reading out of range on the fuel mix.
You then replace them because thats what the code is for, only it will come back because that was not the problem.
And with 75,000 miles I am betting they are the original spark plugs and wires.

 

The mechanic actually suggested changing the plugs and filter. Even told me to do it myself to save myself some money. He literally started at the o2 sensors and tested every wire and PCM plug he could find. He didn't charge anything for that either. I actually didn't get charged for anything. I was really impressed with this guy. Straight shooter who didn't try to empty my wallet. I will order wires too. Thanks for the advice Spike I appreciate it.

 

Sounds like you have a good tech working for you, thats hard to fine these days.
Make sure you buy good plug wires, like STI, Magnecor or Kingsbourne.

 

wow, air filter and plugs, that won't fix ****.

Tell the technician instead of throwing a set of **** on the vehicle to actually look up bulletins.

He might find that the issue is actually a bad issue cat and not a bad set of air filters or plugs.


Plus it will be covered under warrantee by a LR dealer.

 

I had read the bulletin about the cat getting the small crack and asked him to check that. It was fine no crack. I pulled the air filter out today and it was absolutely disgusting. Put in a new one so I am hoping that helps. Showed my brother the air filter and his exact words were I am surprised the thing even starts with that air filter.

 

first of all these cars dont have plugs..... they are coils. second of all the spark plugs should have been done at 60k miles and yes this is a very common problem with these year Range Rover the converters crack at the welds causing and exhaust leak throwing the code most of the time its a hair line crack that will only be exposed when the vehicle is dead cold . if you start the car in the morning and carfully run your hand over the cat welds mostly the pre cat you can feel the air coming out before the metal expands and seals it. bank 1 is passengers side and bank2 is drivers side. GOOD LUCK

 

I believe once you remove the coil you get to the plug correct? Same deal on the Audi we have. If the plugs/coils and air filter don't do the trick I will take it to the LR dealer and have them inspect the Cat. Here is a picture of the absolutely filthy air filter I removed. I can already tell a difference when driving it.

 

If the air filter (which is pretty easy to get to) looks like this, wonder what other filters might be "overdue" ? Clean throttle body and MAF sensor (if so equipped)? Not that these will deal with existing codes, but couldn't hurt.

 

I haven't gotten into it that much yet. I plan on doing the fuel filter and all fluids next weekend. I will check the throttle body and MAF sensor as well.

I just want to get this thing in the best possible shape. I absolutely love driving it.