P1111 is good to hear!

Trims are probably OK but I like to check...

 

dear all,
my old girl has been starting to use huge amounts of fuel and is burning a rich mixture. I plugged my magic OBD reader into the car system and voila, P1647 showed up with the comment, „Heated oxygen control module, bank 2 open/shorted“ appeared. Reading your remarks and comments here helped but … what is upstream and downstream. References taken from the front of the engine are useful but always say if you are viewing from the console or the radiator.
I purchased 2 Denso sensors last year so have a few reserves :-). DOX-0430 might mean something to you all as it‘s the part number. Could anybody let me know if this is the right part for the job and which of the 4 sensors is the right one.

Thanks
Stig

 

Upstream is the one closest to the engine.

 

"Bank 2" is where firing-order cylinder #2 and it's even-numbered brethren reside. Driver's side, US market cars, for the AJ133 gasoline-fueled NA V8 (and not-only).. but have a care as to "convention' and assumptons. JLR did - or acquired - something pre-verted as to numbering on some of the motors they used - went 1,2,3,4 down one side 5,6,7,8 on the other. German thing, was that?

O2 goods are a PITA to get wrench to, age and contamination insults are seldom "localized" with any degree of precision, stuff happens in "waves" once it starts.

One sensor goes and none were anywhere near new?
I kept it simple. Bought all four.

Two new CATS as well, given remaining life is a dice-roll after 100K miles, and if/as/when those get borked sensors cannot command enough upstream change to FIX that, but will make the attempt, "good idea at the time" or not, fail emissions inspection needful flags, even if not running rough.

One wouldn't ask a dentist to pull but 1/4 of a bad tooth at a time, wuddja?

Or is masochism on the installment plan why you are not the only one to have spares to hand, in advance?


Better to take the hit of four in one go, get pissed-off and dirty but once, get it over with?

Best to not even ask .... until we have had time enough to forget ... how much "fun" it was, either, given my "lift" is better known as "jackstands" ... and a bit of fake astroturf carpet so I don't have to chase the sockets I drop clear down the road!

Could be worse. Think Diesel-electric submarine repairs whilst under depth-charge attack, air running out, chlorine intruding off seawater getting at the batteries.. and it should seem a walk in the park?

 

I guess I’ve been lucky or maybe it’s because I’ve just worked on cars that have lived their lives in the south and are not very rusty underneath, but I’ve never had a problem getting out and O2 sensor with just a wrench. I do not doubt that some people that have northern cars or cars with lots of rust underneath. Find it difficult to remove those parts but knock on wood. I havent experience that yet.

But for the question, I was asked an upstream sensor is the sensor that is closest to the exhaust manifold. It’ll be another sensor either in the middle of the Cal converter or after it and that’s the sensor 2.

No, I would swap O2 senses from one side to the other before replacing them just to make sure it’s not a shorted wire and the harness that’s causing the problem

always go with an OEM manufacturer when replacing your sensors because I’ve had little luck with aftermarket

 

Truly! You should sacrifice a goat or sumthin', but it isn't as bad as before "STAINLESS" (weell not really, but close!) got adopted in place of shiddy-shoddy mild steel whatever-alloy was cheapest that week for exhaust systems.

Less work to put a meter on them, but "cold" doesn't tell the whole story, regardless, and the built-in brain's codes actually do a decent job of recognizing failure or "out of bounds" ranges.

I lower my risk by doing the whole circus in one go to reduce likelihood of annoying piecemeal failure aannnnd improve the odds of calibration being a better match.

Back when I had cause to add Sta-Bil or similar and have a vehicle set for a year or two between fresh fueling, O2 sensors didn't last very long, either. OTOH, there was but one, not two or four.

Mate of mine lucked-out on a late 1940's MG roadster "TC" or "TD"? barn-parked with the recommended full tank, close to half a century earlier.

Not a solvent he could find as would remove the "plastic" it had become down where the bottom plumbing sat to save that otherwise pristine tank. Eventually had a new "slab" type fuel tank fabbed from bare metal.

Motor fuels have some right nasty chemistry in their two-dozen or so components, much of it hostile to sensors if we let it be so. Same, again, some so-called "system cleaner" snake-oils.

 

Aarcuda,

I replaced the two cited above with: DENSO2349030 just about a year ago & everything went great. Rockauto delivered ahead of schedule & the installation, thanks to Jag Forum help, was on the easier side.

Good luck,
Steve S.

 

First started using Rockauto, I was kinda embarrassed over being sech a cheapskate.

Came to find out the computer at the local major-chain brick-and-mortar parts house had a link to Rockauto, too, and now and then made use of it.

I quit feeling like a miser.. kept checking Rockauto first for their easy to use website and good parts info.. but soon also found even lower-cost sources!

Keeping "vintage" motorcars sweet - any marque - is only about fifty-percent research and wrenching.

The equally important "other half" is thoroughly researched and sharply-focused purchasing.

 

Trying desperately to figure out intermittent "restricted performance" message. Bought a new icarsoft scanner, just learning the ropes. Can anyone help with the following?

P0171 and P0174, lean on Bank 1 and 2

From reading through the forums, I see how critical the O2 sensors are. When checking the sensors with the scanner, car running, and comparing the two downstream sensors, there is one that doesn't seem to be working, but there is no fault code for it. Can this happen? Could it be malfunctioning but not throwing a code?

The selection was "oxygen sensor heater open/short circuit monitor downstream BANK 2." When comparing it to the other one, this one shows a "0" all the time, while the other toggles between "1" and "0" back and forth.

I don't even know what the 1's and 0's mean. Can anyone help?
Cheers
PS. I also called up the "oxygen sensor heater deterioration monitor downstream" for both, and they do both toggle between 1 and 0 realtime.

 

Have a look at threads about those codes and fuel trims - to see if what you really have (as most likely you do) is an air (vacuum) leak.

If you do then don't worry about any O2 sensor till you fix the leak.

 

Had Power loss of about 50hp and torque trough upstream right bank1 because of the o2 sensor electric connector on xj8 4.2 na.
the sealing inside was crumbling and parts of it stuck so it bad bad connection

 

I think the the O2 sensors were the Second thing I did when I got my 04, after replacing airbags with cheap chinese ones (poor choice BTW), I had a code for one, and after the first replacement failed and the code for the second sensor appeared, I went for broke as has been advised and replaced all 4 with Denso's. They are easy to reach from underneath -I recall using a regular wrench- and it went well as my car is (apparently) rust/ corrosion free. They have not failed Yet. Touch wood.

 

Thanks for the posts.

I have learned more since my post above. I have been looking into a possible vacuum leak as well as faulty O2 sensor(s). Let's see if you more experienced hands agree with my analysis:

1) Apparently there are at least 44 separate codes specific to O2 sensors. I would assume that if one was not functioning, I would see some code specific to the sensors, which I am not.
2) In order for the fuel system to go into Closed Loop, the O2 sensors have to be working. After warmup, my car DOES go into CL on both banks. Doesn't this mean that the sensors must be working, and correctly?
3) I watched a video last night about how to determine if you have a vacuum leak by looking at the Short Term Fuel Trim and Long Term Fuel Trim real-time. Basically, if there is more air going into the system than the Mass Airflow Sensor measures, the STFT will compensate by adding more fuel, then that will be transferred to the LTFT, and you'll see a higher percentage of LTFT than there should be, and you can test that by revving the engine and the LTFT will then go down, since the relative percentage of extra air from the leak will be lower. I have yet to try it on my car, planning on doing that today.
4) I also got a cheap fluid handpump - saw video how to do a smoke test to locate a vacuum leak, also have yet to do this. Question: it seems to me that if you introduce the smoke into the main air intake, that the smoke won't be able to go any further than the throttle butterfly valve, right(?) because that valve is closed when the engine isn't running? So how can you get the smoke further into the vacuum lines so you can potentially locate any small leaks? (I have inspected absolutely every line that is accessible and visible, so any leak will be very small and hard to find.) You can't start the engine because that will just suck all the smoke through. You can hook up the smoke tube to another line somewhere downstream of the butterfly valve, but how is the smoke going to go through the system if all the other head valves, etc., are closed? I don't see how the smoke is actually going to go through all the lines. There's a whole engine in the way, with closed valves, pistons, etc.! Seems like getting smoke into all the lines would only be possible if there was an open path all the way through to the exhaust pipe, but there isn't.

BTW, the P0171 and P0174 only come up intermittently, and not very often. Seems like they happen under lower-demand conditions, certainly not when doing hard acceleration. I also cleaned the "Part Load Engine Breather" (non-PCV valve) according to the Technical Bulletin. It was not clogged or even dirty.

I put the car on risers and crawled underneath to inspect the whole exhaust system (and everything else I could see). I am lucky to have a car that was never subjected to corrosive conditions, so the O2 sensors and the whole exhaust system look virtually new. None of the O2 connectors or wires or sleeves are even dirty. Most components are shiny and new-looking. No signs of any seals leaking, or a single other item that looks physically compromised in any way.

Seems the main way to troubleshoot and diagnose these cars is by using the scanners, not by old-school troubleshooting and inspection and process-of-elimination guesswork.

Thoughts?

Update: Just did the Fuel Trim observations vacuum test. All Fuel Trims seem to operate within normal expectations - they don't seem to indicate a vacuum leak, or at least not a significant one. Max LTFT percentages were 5.5 for both Banks, no significant excursions of STFT.

 

To go CL the O2s don't have to be working particularly well or to be happy about the air/fuel mix (well, always recall it's just the O2 they can sense so there could be no or lots of fuel and no sensor knows).

At idle with a hot engine: if your STFTs aren't moving much from zero (so their values aren't changing the LTFTs) then it's worth looking at LTFTs and if they're not far from zero (5ish is ok) then it's unlikely you have an air leak or at least not much of one.

If you get lean codes P0171&P0174 despite the above consult the Jag DTC PDF and look at all the other causes than (unmetered, i.e. after MAF) air leak. Unlikely to be bad O2s if you've Denso ones as both banks don't go bad at once.

When codes flag you also get freeze frame data and it can be worth reading as a clue to what conditions are at the time. Such as RPM, speed & Load.

An example of misfire codes (could also be called unexpected O2) is one or more bad coils or exhaust leak but mostly you won't get BOTH codes.

If you just get one code it can be because the other is close to flagging but hasn't yet so don't assume one code means that's the only issue - but also don't assume the other is about to flag. The trims / freeze frame can help.

(Had your LTFTs been much larger it would be worth revving to see if they then drop - classic sign of air leak.)

 

Thanks, JagV8.

That's a wealth of useful information. I didn't know the freeze frame worked like that. I have erased the codes already from the last time it happened, but I will check next time.

I did record a video of the scanner realtime data, will try to include it here. First run-through of the scanner pages is engine at operating temp, at idle. Next, I revved it at each page to see what the numbers did. Toward the very end, you can see it go into OL Drive briefly. The STFTs do go up with revving, but then go down - briefly below the idle number. I would guess it looks like normal functioning, but it is just that - a guess. Can you identify from this if you would consider there may be an air leak or not?

Cheers

See if this link works: https://share.icloud.com/photos/0b0-...HTN9-xTiKCw5tg

 

From what you say, sounds normal so next I'd want to see when the codes flag i.e. what's in the freeze frame data.

 

Will do.
Did the link of the scanner data video work? (First time I've used that function, just wondering for future sharing of video.)

 

As a followup for anyone who's interested, or having similar problems, I found the "non-PCV" Valve connector to be ever so slightly loose (but still firmly seated in the valve cover). There was some old sealant that I scraped off around the edges. I resealed it with gasket sealant. I have not gotten the restricted performance message since then, or any other messages, and all other items like the O2 sensors, etc., check out to be operating normally according to the scanner. No codes. After a few weeks of occasionally driving it, and going through almost 2 tanks of fuel, I am hesitantly claiming success!

I am really surprised that such a miniscule hairline sealant "crack" could possibly be enough to let in enough extra air to make any difference. Easy fix, ultimately, but it sure was hard to identify.