2011 X5 50i oxygen sensor question

[80stech]

The TIS has a ton of good information on how the diagnostic codes are set, most is listed by P numbers though. Here is a sample, the flow chart didn't copy.

EXHAUST GAS SENSOR MONITORING > 5.3 NOX SENSOR DS LAMBDA SIGNAL > 5.3.2
LAMBDA SIGNAL MONITORING DURING OVERRUN (P229F)
General description
To eliminate the Nox Sensor monitoring concern, BMW included a diagnostic that monitors the response of the
oxygen measuring component of the Nox Ds Sensor during fuel cut.
If the test conditions are satisfied the signal is compared with threshold values. If the signal is above/below a
threshold a fault is detected and a preliminary DTC is stored. If this fault is detected in two consecutive driving
cycles, the M L is illuminated.
Flowchart
Fig 1: DTC Storage Flowchart (Lambda Signal Monitoring During Overrun)
Courtesy of

[80stech]

2c2d in hexadecimal converts to 11309 in decimal btw which looks like it could be a BMW fault code. The Bentley manual for the E53 shows the BMW codes and equivalent P-code but I don't know if there exists something like that for the E70. BMW diagnostic software (with TIS built in) might even show you the correct flow chart (and maybe even wiring diagram and diagnostic strategy) for the code retrieved.

[Zaner]

After clearing the codes it varies as to how long it takes to return. Usually one to three drive cycles, sometimes I take it around the block once and it pops on. Sometimes I take it around the block three or four times and then it pops on. Style of driving doesn't seem to affect anything. And I agree this seems to be a deeper issue someone chased. I just wonder how deep can it be cuz man it sure seems to run and drive great. No odd smells, no smoking, it doesn't leak anything, no strange noises. Being a novice with BMW... From the outside you see a nice pretty car that looks very well taken care of on the inside and outside and a big fat stack of maintenance and repair records. And you think to yourself man this is a good buy somebody really cared about their car. And then you own it for a few days and you start seeing chinks in the armor..

I did see along with new downpipes and catalytic converters it got reman turbochargers installed last year as well. All this was done at a BMW dealership in Oklahoma called Jackie Cooper BMW

Before coming on here and asking the question I did quite a bit of exhaustive research on those codes and it said any number of things could be wrong with it. Vacuum leaks and exhaust leaks, spark plugs, oxygen sensors ,injectors, even saw one guy had a piston ring issue, you name it it was suggested that this code could be caused by it lol. That's why I ultimately ended up here hoping I could talk to some people that were experienced and maybe some have been there and done that

[ard]

BMW v8s had an issue where injectors were mismatched- enough to let a cylinder here or there run very rich- car would run fine, but the engines would grenade when oil was diluted with the gas from these rich cylinders.


I bring this up NOT about your issue, but rather as an observation that 'it doesnt smell' or 'it doesnt smoke' or "runs great" is not a reason to ignore (or not be very concerned) about codes or CELs. Bad things can be happening.


Just an FYI.


Can you run a vanos functional test on the code reader you have? Slaggy VANOS solenoids/actuators can result in AFR issues, which can be very sneaky- it isnt a set thing, but at some parts of the RPM band, you are running rich. So it doesnt always happen the same. The fix is popping out the vanos solenoids, flushing them hard with carb cleaners and actuating the, with the proper voltage, then reinstall w new orings. Solenoids get fouled when people dont change the oil o time. A BMW specialty.



One final thing- but I am guessing you saw this- since BMW motors all share the same functions/componentry, dont focus only on "X5 w V8"... lots of other BMWs share these issues.


How many prior owners? All of them baby it, spend a ton of $$ and over-maintain it? Could have been a deadbeat owner in there. Also, BMW dealers can suck- the "BMW Maintenance" is notoriously poor- oil change intervals that are WAY longer than is healthy. Dont think because it was serviced at a dealer this buys you something. Its good that the serious repairs were at a dealer and may have a warranty on this work

[Zaner]

It was a one owner vehicle that a loca.dpctor owned...I agree the issue shouldn't be overlooked just because it seems to run so good. But to a simple man view point it almost wants to trick you. I have 4 other vehicles I have as daily drivers, I bought the X5 more as a fun little toy to tinker with. So I'm happy for it to sit there until I get it straightened out. I will look in that scan tool and see if it will do a Vanoss test. I guess in the worst case scenario even if I can't do that test I could always just pop them out and clean them up real good as you suggested. I did see in the warranty work that the heads were pulled off and redone last year as well because they suspected a valve seal issue. And the cooling system hoses and such were redone at the same time. I was told when I called the local dealership that all the work they performed last year was still indeed in warranty. But they couldn't tell me whether the issue I was currently having would be covered by that warranty.. and if I drop the car off I could be subject to fees if it's not.... In the past tinkering with cars I've had a lot of success being a part of forums like this because a lot of you guys have been there and done that. I will certainly tinker with that Vanoss situation over the weekend. And again I appreciate your help thus far

[80stech]

If you haven't already, have a look at HomerlovesBeer thread. It might take some commitment on your end but nothing is impossible
Do you not already have a diagnostic laptop for working on your "powered" cars ??

[Zaner]

I do have a laptop that's running an old version of HP tuners. But I looked at the HP tuners website and they don't offer any support for BMWs. I even sent them an email as to why because they do Lexus and even Mercedes-Benz and they said that there's not a high enough demand for them to put out a version for BMWs LOL. I will look up that thread that you mentioned. I bought this BMW knowing it would probably be a bit of a challenge but I did underestimate it a little bit I think LOL. As you mentioned earlier if the dealership couldn't get it figured out after 15,000 plus dollars, chances are is probably not something simple. That a simple guy like me will figure out easily. But I'll keep plugging away at it and see where I get. Thanks again for your help

[80stech]

I ran across this in the TIS (which I obtained from a member here and am ever so grateful even though this is for the newer facelift which mine isn't )

I've recommended Stabilant 22A on this forum before but it came from a very small Canadian company back in the day, for a niche market, so I'm surprised to see it now used and recommended by BMW.

The oxygen sensor gets it's reference from the air space around the wires going into it, if there is a sleeve around those wires that is sealed to the sensor then the reference comes from the end of the sleeve but it sounds like now the sleeve is sealed around the connector as well ?? Are the connectors not sealed then?? Under the heading of "bizzare things maybe not thought of or tried" maybe cutting a slit in the sleeve is needed ?


3.0 ELECTRICAL CONTACT ENHANCER AND CONTACT CLEANER > ELECTRICAL
CONTACT ENHANCER
Stabilant 22A evaporates and leaves a thin polymer film which is conductive between the mating
surfaces, while staying non-conductive between adjacent pins. At the same time it prevents the
formation of any further harmful deposits.
Wurth Part No. 893622 (Stabilant 22A)
Note 1 : Stabilant 22A must not be used on Oxygen Sensor connectors. To function, oxygen sensors
require a flow of oxygen through the terminal connector to the sensor element. Stabilant 22A will affect
this flow of oxygen, and will result in irreparable damage to the sensor.
Note 2: Stabilant 22A must not be used on plug connectors which carry fiber optics. Stabilant 22A may
migrate to the fiber optic and attenuate the optical signal.
3.0 ELECTRICAL CONTACT ENHANCER AND CONTACT CLEANER > CONTACT
CLEANER SPRAY
Use to clean electrical and electronic components of dirt, grease, etc. Will not harm components or
epoxy coverings. Allow to air dry. Do not dry with shop air supply as this may contaminate the connector.
Wurth Part No. 89365 (Zero Residue Electrical Contact Cleaner)

[pshovest]

Those codes are pre-cat O2 sensors for both banks.
Overrun means closed throttle while coasting. DME shuts off fuel under these conditions and O2 sensor output should be near zero. You may have leaking fuel injector(s) or oil blowby getting into the exhaust that O2 sensor sees. Use live data on a ODB2 scanner and look at O2 sensor voltage while coasting.
Too much air might cause this also. Does throttle close completely? Any vacuum leaks between TB and cylinder head?

The 50i's are massive oil consumers. How much oil does yours use?

https://bmwfault.codes

[Zaner]

Wanted to update on a resolution...did some digging and found the driver side air intake was not fully pushed on. So i slid that on and secured it. Didn't really fix all of the issues but it was a good find. I remember the previous owner saying they had recently replaced both O2 sensors with Bosch brand. Which I had heard good things about that brand. I did pull those O2 sensors and indeed they look brand new. Just for a hunch though I ordered two brand new OEM BMW O2 sensors off of eBay. I installed them and instantly all of my issues went away. Black exhaust tail pipes, would look like black fuel spitting coming out the tailpipe and getting all over the back of the vehicle, the check engine light coming on all the time everything seems to have been resolved by putting into OEM O2 sensors and putting that air intake hat on the driver side. I did notice when I pulled it apart there was about a tablespoon of oil in each air filter housing... I've just been keeping an eye on the oil level and keeping it topped off. I guess these vehicles just really appreciate OEM sensors. It's been running great for about 2 weeks now