I hate my life. (O2's/MAF woes on D2)

[LeeKelley]

P0150 and P1172

That's what I have left of my list of codes after replacing my plug wires, plugs, and Bank 2 O2 sensor. (not all related to the above codes, just updating on what was replaced today)

Any thoughts? I'm thinking since the 1172 indicates lean on bank 1 and 0150 indicates a "sensor malfunction" on bank 2 (which is brand new and installed correctly)... well, I'm really near the end of my own reasoning actually. I'd love some thoughts.

Symptoms/Facts:

• Running a little rough on idle
• Smells of rich Amoco Fuels
• Swapped an MAF with a buddy for a little while and still had the same symptoms (full disclosure: his isn't exactly running like a top either...)
• Positive there are NO leaks from air box to throttle body
• Probably minimal exhaust leaks in the manifold to Y-pipe connection, but not enough to hear or feel
• My OBDII reader reads a signal from my MAF when it is plugged in from 6-8ish (units?) as opposed to the 0 signal when unplugged.

I just really wanna figure this out and post an update that this (whatever I find) was the cause and now my rover loves me again, because I've found lots of people online with extremely similar problems with about 5 or 6 suggestiony replies and never any definitive answer and confirmation that something actually cured the issue.

Thank you in advance to the guy that actually reads this and takes the time to post a reply!!!!


2004 Discovery SE

 

[mbrummal]

from the RAVE manual:
P1170 Downstream fuel trim malfunction (bank 1) Front sensor aged - rear HO2S adaption too lean/too rich LH bank (NAS and EU-3 only)

P0150 O2 sensor circuit malfunction (bank 2, sensor 1) Front sensor RH bank stoichiometric ratio outside operating band

Do you have an air leak at the SAI vacuum canister on the passenger side of the engine bay? Or possibly the brake booster hose where it goes into the upper manifold?

 

[LeeKelley]

Possibly?... Do you know a good way to check for a leak in the Secondary Air stuff? And where exactly is the "Brake Booster Hose"? I know that there's nothing obvious, because I've definitely hunted around that area for leaks of any kind trying to diagnose this issue before, but other than looking really closely, I'd need a good way to check for leaks.

That's certainly a good thought, and could be the issue.

 

[mbrummal]

look at the black cylinder on the passenger side near the firewall. It has a few hoses that go into it and they can pop off.

The brake booster hose is a hard nylon line going from passenger side of the upper intake manifold to the firewall and then over to the brake booster. It usually has a red ring on the fitting where it goes into the manifold.

where are you in auburn/what color is your truck?

 

[DevilDisco]

Check your 02 sensors and ensure no oil has fouled the connection. I had this happen recently as well. Oil ran down the exposed part of the rocker cover gasket and down the wire that connected to the 02 sensor and fouled it. I used some MAF cleaner to clean the connections (both sides male and female) and swapped in an older plug I had from when I replaced my catalytic converters. My symptoms however appeared when the engine was hot and I would stop at a light. The SES flashed and stumbled pretty bad on acceleration. I have yet to put in the newer plug but the issuse had not appeard since I cleaned the connection. How many miles on your vehicle?

 

[LeeKelley]

First, some Answers:

I drive a silver disco with black wheels and a black hood. I'm all over town, all the time.

There are over 130,000 miles on my car.

Brake Booster hose looks secure into manifold and appears like it's in good condition.

Black tube with hoses are all attached and at least appear to be not leaking.

The connection area that the O2 sensors are plugged into are indeed EXTREMELY oily and grody. I've feared that it could be an issue.

I will go right now and do what I can to clean up the connection with some brake cleaner/engine degreaser (that's all I've got on hand). My problem is how in the hell you reach down into that area (I can barely get to the connection that comes off of the rover with the ends of my fingers) and do much good cleaning wise?... We'll see how it goes and I'll report back any findings.

Thanks for all the replies and suggestions!

 

[gmookher]

okay

whats the right age to pre-emptively swap out all four 02 sensors ? 80k? 120k?

 

[LeeKelley]

Sweet Mother of Pearl! I got in there and scrubbed that thing down with a toothbrush and some brake cleaner and magically I now have a reasonable signal from the O2 sensor on the passenger side! (I saw the value on my OBD2 reader) THANK YOU DEVILDISCO!

So here's where I am:

Idles 100 times better

Still a little stinky

according to OBD2 reader I've still got a high (pegged at 25) long term fuel trim on my passenger side bank (may be due to my exhaust leak that I now hear more prominently with it idling and running smoother)

Interesting thing... I now have a code that's popping up and saying that I have CKT Malfunction on that same O2 sensor, but I'll sit there and watch the voltage reading coming from that sensor and it is normal and functioning???

I will drive it a few more drive cycles and give an update as to whether its totally healed or whether I've still got some bugs to work out.

 

[LeeKelley]

True, true... You probably SHOULD preemptively swap out all four to avoid some of these annoying issues (however, even with the brand new O2's I would still have those connection fouling issues), but I'm a baller on a budget here! I can't afford several hundred dollars worth of "just in case."

 

[DOHC Holliday]

When I swapped the Y pipe on my truck I ended up with codes afterward. A wire had pushed through the O2 connector on the vehicle side of the harness. May want to make sure none of your pins have pushed back into the connector and are making good contact.

 

[djrover]

I have read that you can search for a vacuum leak with the engine running, by moving the burner end of an UNLIT propane torch along the vacuum hoses and fittings. When the engine revs up you found your leak.

1st: Reread the word in capital letters.
2nd: Take common sense fire prevention precautions: Do this outside, not in the garage under the nursery. Only try this in the absence of fuel leaks. Have an extinguisher nearby. Only attempt this before your third beer. You get the idea.
3rd: I read this - I did not try it.

All the best
DJRover

 

[LeeKelley]

CONCLUSION:
​

I wish that I could point to one specific sensor that was definitely my problem instead of what I'm about to say, because like most Land Rove issues, this might have been a case of several things working together to make my life miserable.

I have:

• replaced both Upstream (pre-cat) O2 sensors
• replaced the MAF
• cleaned O2 sensor connectors coming from vehicle (very important)

Results:

• No Check engine light for more than a week of driving, so far!

Important Note: When I purchased and picked up the Bosch MAF from Autozone ($150ish) they gave me the incorrect sized housing! It had the correct part number on it for a 2004 Disco, but it was not the right size by about 4 or 5 mm. Weird... But, the actual sensor was correct, so I used the weird security star 5-point driver to take the sensor out and put it in my old housing. Strangely enough, the screws that held the new sensor in the wrong housing were 6-point security stars making it just the right amount of annoying.