Hi all. Gregg here!

My '99 failed emissions test for the 1st time last month. Initial OBD II codes indicated that the MAF was faulty and it was replaced. Very shortly thereafter the SES light came back on. I had the OBD II codes re-read but was surprised to learn that what I thought were "generic" OBD II codes, i.e. having the same meaning in all vehicles, is NOT the case with the Discovery II.

After replacing the MAF these are the codes I got:
P0174
P0171
P1172
P1175
P1590

If you look up P0174 (P0171) on Google, say, you'll discover that it represents "System too lean (bank 2)" ("System too lean (bank 1)" for P0171) (see http://ezinearticle s.com/?id= 1865946). However if you search on P0174 in the Rave manual you'll find "System too rich (bank 2)" ("System too rich (bank 1)" for P0171).

This was surprising to me and contradicts the "generic" idea. Could the Rave manual be in error? I think not.

Now, when I search Google on P1172 I just get confused since that appears not to be a "generic" code. However, the Rave manual has no doubt it means "System too lean (bank 1)" ("System too lean (bank 2)" for P1175). What? So I'm both lean and rich on both banks simultaneously!

So in conclusion I am confused by, (A) the Discovery II OBD II codes appear not to follow the protocol, and (B) I'm rich and lean at the same time. I have been told that most likely I have faulty O2 sensors, all four. You agree?

I look forward to your comments.

 

Where did you get your MAF???

 

You are running too lean on both banks.
Did you buy an actual Rover, in the box MAF or a cheap replacement, if so, that is your problem.

 

I purchased the MAF from Atlantic British. Come to think of it, I remember the salesman suggesting to me what MAF to buy. He said something to the effect that what he had was just as good as an OEM unit, probably made by the same manufacturer, but not with the Land Rover sticker on it.

Here's a link, http://www.roverparts.com/Parts/ERR7171G.cfm

He said that was the MAF he mostly sold. I find it hard to believe that AB would be hawking a lousy MAF product. But I do not rule out that the one I got was bad.

I ordered another part at the same time, but got the wrong item in the box. Now I wonder if the MAF I got might be the one for a later model DII. Hhhmmmm, maybe I should pull it out and take a close look.

You sure it's the MAF?

 

For less then that price, you can buy a new Rover, in the box, MAF from Tont at , http://www.lrrforums.com/store/index...ategory_id=297

 

This Bosch MAF from AutoPartsWarehouse,

http://www.autopartswarehouse.com/sk...%26+Drivetrain

is $128.95 and promises to be a direct replacement for the '99 DII.

The MAF I bought from Atlantic British,

http://www.roverparts.com/Parts/ERR7171G.cfm

is $217.95. I'll be darned!

If I have to try another MAF I'm inclined to give the APW Bosch a go. You agree?

 

Mike, thanks for the link to ARB Wholesale. Looks like MAF prices vary a lot.

But for the moment let's say the MAF is OK. My mechanic, before replacing the MAF, "smoked" the airways and found no leaks. No leaks, good MAF, say. What could be wrong?

Is the next suspect the Idle Air Control valve? Or the Secondary Air Injection system?

 

I just went out and looked, the part number on my 99 D2 MAF is 0-280-217532, check your and don't buy any thing that doesn't have that Bosch part number.
Also a year ago, I saw an invoice on a replacement MAF and the shops cost back then was around $155 so how can someone be selling a true Rover MAF for less?

 

FYI I bought a MAF from That site and it was bad. I bought a new one from AB and so far it is fine. Call them back and tell them you want you money back, and get it from AB. Trust me it made a huge difference

 

At long last, my '99 Discovery II has new long overdue emissions testing stickers on the windshield.

Allow me to review.

In August my truck failed emissions testing. The codes indicated a bad MAF. I purchased a non-OEM replacement MAF from Atlantic British. It was installed and the truck still failed, but now with different codes (see above). My mechanic spent several days at various times trying to figure out what was wrong to no avail. People I consulted with said, "replace the oyxgen sensors," even though the codes were not indicating that they were bad. I bought all four sensors, again from AB, and intended to install them, but never had the time (busy painting my house).

In the meantime, my wife, who drives the truck on a daily basis, made an appointment with the dealer (Ascot Motors, Sewickley PA) where we bought it, although they no longer sell Landrovers. But the service manager (Kevin) and one senior mechanic still work on Landrovers from old customers. Make a long story short, they read the codes, concluded the MAF might be at fault and replaced it with that of another Landrover in the shop for unrelated service. Lo and behold, over nearly three days of testing the codes remained clear and the truck passed emissions testing. Sticker went on. Big relief.

Let me say, Disco Mike called this one correctly. He said the MAF was the culprit and was very skeptical of the MAF I had purchased. I was surprised because I had a hard time believing I'd get a bad MAF from AB. I was wrong, Mike was right.

Thank God I never installed the oxygen sensors because Atlantic British has agreed to take them back w/o a re-stocking fee and replace the MAF or refund me. Awefully decent of them. And good business practice too, because I have already placed another, different order with them.

So, the moral of the story is, use genuine OEM replacement parts! And listen to those who have a record of knowing their stuff.