Discovery II Diagnosis - OBD Codes

[jbf]

My 2000 Discovery II is reading:

P0150 - O2 Sensor Circuit - Bank 2, Sensor 1
P0174 - System too Lean - Bank 2
P1174* Pending - Something to do with Lamda control - Bank 2

I cleaned my MAF with the CRC cleaner because it was cheap and easy, but the codes are coming back. If it were the MAF sensor, wouldn't both sides read as bad? More info:

Long Term Fuel Trim
Bank 1 - 1.6%
Bank 2 - 25.0%

Short Term Fuel Trim
Bank 1 - 0% +/-
Bank 2 - 25% and does not move

I am considering changing the Bank 2 #1 O2 sensor per the P0150 code. Any other recommendations out there?

[Disco Mike]

How many miles on the truck?
After you're cleaning of the MAF, you may need to replace it also, Bosch MAF's don't take to being cleaned.
Mike

[jbf]

Originally Posted by Disco Mike

How many miles on the truck?
After you're cleaning of the MAF, you may need to replace it also, Bosch MAF's don't take to being cleaned.
Mike

113K miles on the truck. We have owned it since new and I believe the MAF is original. My local independent parts store (not a Land Rover specialist) thinks I should run some Techron to clean the injectors first. He says O2 sensor faults are usually indicative of something else. Your thoughts?

[auwesman]

It's probably time to change the MAF, but generally you get an incorrect gear ratio code as well with bank 1 and 2 lean codes.

I know I cleaned my MAF a few times, and it would only go a few thousand miles before it threw the codes again, so cleaning it isn't the answer as Mike said.

I'm not so sure about the techron. Do you use 91+ octane normaly?

[Disco Mike]

Normally 02 sensors are pretty much in need of replacement once they clear 100,000 miles, so even though you may only have one fault code, I wouls replace the four of them.
Techtron is pretty good especially when used while at highway speeds, if you can find some B&G 44K additive, send the extra money and use it.
Mike

[jbf]

Originally Posted by Disco Mike

Normally 02 sensors are pretty much in need of replacement once they clear 100,000 miles, so even though you may only have one fault code, I wouls replace the four of them.
Techtron is pretty good especially when used while at highway speeds, if you can find some B&G 44K additive, send the extra money and use it.
Mike

The DII appears to be running fine and my primary goal now is to clear the service light for sale of the truck. If I want to be cheap, what order would you proceed on the options mentioned below?

- B&G 44K (or Techron)
- new MAF
- new O2 sensor for bank 2, sensor 1 (is this the front sensor?)
- new O2 sensors all around

Thanks, your advise is appreciated.

[Disco Mike]

There is no such thing as going cheap on your Disco.
Mike

[ealex]

1. Techron / BG44 ~$10
2. Oxygen Sensor ~$60 (atlanticbritish.com)
3. 4x Oxygen Sensor ~$240
4. MAF Sensor ~$250

I'd hold off on the MAF - it malfunctioning should lead to both banks running lean or rich. And both banks would be either rich or lean.

[auwesman]

What year is your truck? I didn't see it on this thread but I may have missed it.
If it's a '99 - '02 MAF is only $145. But I'm also not totally convinced it's the MAF (even though you may as well probably change it out of preventive maintainance).

[jbf]

Originally Posted by auwesman

What year is your truck? I didn't see it on this thread but I may have missed it.
If it's a '99 - '02 MAF is only $145. But I'm also not totally convinced it's the MAF (even though you may as well probably change it out of preventive maintainance).

It is a 2000 Disco II with 113K miles. Since the codes all read the problem is confined to bank 2, I was drawing the same conclusion.

[Rovin4life]

start with the first oxygen sensor.

its readings could be off enough confusing the pcm.

if you still have a lean code then check for the air leaks on that side.

if no hoses are broken then its possible you have a bad intake gasket, that kinda diag is a bit more difficult to do but various means can be done including using a can of propane, basically if a leak occurs the propane will be sucked in and the vehicle will run a bit diferent.

[jbf]

Thanks for all the advise. Can someone confirm for me:

Sensor 1 = pre-cat
Bank 2 = right (passenger) side

AND finally, among all the brands available, are Walker sensors any good?

[Disco Mike]

You are correct, but with your mileage, you should replace all 4. I believe Atlantic British still has them on sale for $59.
Mike

[buick215]

Rather than waste money on oxygen sensors,why dont you just swop front sensors from side to side and see if the codes and trims move too ?
If the engine has had decent fuel and servicing there is no reason why the sensors should be all dead.Its a waste of money and raw materials too.
Diagnose it properly and only replace what doesnt work.

[Elemental]

Originally Posted by buick215

Rather than waste money on oxygen sensors,why dont you just swop front sensors from side to side and see if the codes and trims move too ?
If the engine has had decent fuel and servicing there is no reason why the sensors should be all dead.Its a waste of money and raw materials too.
Diagnose it properly and only replace what doesnt work.

Spot on brother!~