So, what have you done to find your 2 codes, when was your engine last tuned along with new 8 mm silicone wires, what octane gas are you burning and have you checked for both vacuum and exhaust leaks?

 

Update, kind of.

I replaced the O2 sensors, and with the engine not yet fully hot yet, Bank 2 Sensor 1 seems to be switching fine at idle, Bank 1 Sensor 1 seems to be static until I blip the throttle, then it dips to about .2 and then back up to about .7. Not codes yet, but I haven't yet taken for a drive, big storm just hit, I will test drive tomorrow. This still seems a little odd? Should they both be switching significantly at idle (would it matter that the engine was still cold)?

There was some black specs (soot) coming from the exhaust and slight sulfur smell. I assume this was due to running rich with the bad O2 sensors. I'm not convinced that the O2 sensors were my only problem, but I still can't find anything else. In the short time after I replaced the O2 sensors, the engine seemed to still put out some black dust with higher revs, but maybe this was build up from before (no smoke, just some dust on the driveway near the tail pipe)?

Mike - 8mm wires were done about a year and a half ago (I think I used STI, can't remember), as were plugs, and other misc tune up. I am running premium gas (I think its 92 or 93 octane). I have looked for vacuum leaks and exhaust leaks but haven't found anything (maybe I am missing something)...

MAF shows about 1.1lb/min with the engine cold (didn't have time to get the engine up to temp).

Any other ideas? I presume I need to just test drive it for a few miles and see if I get any codes? If it is still running rich due to some other cause, can this cause my new O2 sensors to fail (clog with soot)?

Sorry for all the questions.

THANKS!

Lee
2000 Discovery
90,000 miles

 

What sensors did you put in?
If not Bosch, then you may be heading for problems.
If some odd ball china sensors then...

Don't put in NGK crap, or Fischer or any of this odd ball stuff.


Amazon.com: discovery o2 sensor

 

Jfall, I have only used the Bosch (15175) from Amazon, both times...

Question - I assume the black soot and smell I was seeing was from running too rich. If I had a vacuum leak sucking unmetered air into the intake, wouldn't that make it lean and not rich??? Or am I over simplifying it (maybe with unmetered air and/or bad O2, the mixture just gets way off rich or lean). Any thoughts on this (I was hoping to eliminate vacuum leaks - I can't find any, but my mixture is obviously off)...

Any input would be appreciated. THANKS!

Lee

 

I hope you sent one set back cause they have a 1 year warranty.
Have you made sure both connections are clean and free of oil?

 

I had replaced the O2 sensors (Bosch from Amazon) about 3 years ago. Then when I got codes about 2 weeks ago, I replace them with Bosch from Amazon, and then got more codes, and yes, those were replaced under warranty. Connectors are clean.

Mike - any thoughts on my mixture question? Would a vacuum leak allowing unmetered air cause a lean scenario and NOT a rich scenario??

Thanks

Lee

 

Update: so I have driven a few miles on the newly replaced O2 sensors, and all my original codes came back, with the exception of P1171, see codes below:

P0130 O2 Sensor Circuit (Bank 1 Sensor 1)
P0150 O2 Sensor Circuit (Bank 2 Sensor 2)
P1129 O2 Sensors Transposed ???
P0174 Lean (Bank 2)
P0171 Lean (Bank 1)
P1174 lean?

I took everything off from the air filter to the intake (including MAF), and didn't find anything unusual (no cracks or air leaks that I could see), and then re-seated everything.

Right after I had replaced the front O2 sensors, they seemed to be switching somewhat normally (from about .2 to .8), but now that I have codes again, they are sitting at about .2 until I blip the throttle and then they drop slightly. I have changed O2 sensors twice, with the same results; something else must be causing this problem. Are these O2 sensors now ruined?

Any other thoughts?

Stumped... Thanks.

Lee
2000 Discovery