...I'm getting code P2272 indicating Bank 2, sensor 2 problems, stuck lean. So I replaced the associated O2 sensor in the upstream (post catalytic) exhaust location. I disconnected the battery to reset the OBDII computer monitor. Car runs a lot better since the injector replacement, but I'm still getting the P2272 code and can feel intermittent hesitation (not bad but noticeable).

OBSERVATIONS:

1) Bentley says: "P2272 | 2C6C | 02 Sensor Signal Stuck Lean (Bank 2 Sensor 2)" -- That's the SIGNAL and not the O2 Sensor itself, so any electrical fault in the connector or wiring -- anything between the sensor and the DME, can affect the signal and set that code. Apparently it was NOT a fault in the sensor itself, 'cuz you still have the code after replacing. BTW, do you have an SES light? Did you CLEAR the code by connecting to the DME with a scan tool? Any generic scan tool will clear that code (ignition on but engine OFF). If it returns you almost certainly have a wiring fault as getting a bum sensor out of a new box usually doesn't happen.

BTW, that is a Generic SAE code (as is ANYTHING beginning with "P2"), so it MAY not provide very insightful diagnostic assistance and certainly NOTHING SPECIFIC for our BMW's. It appears to be intended to warn of a fault in the sensor or its associated wiring, that prevents the Post-cat O2 sensor from flagging the DME when the cat is NOT functioning properly on the rear exhaust manifold, cylinders 4-6. Any fault in that sensor or its associated wiring should NOT affect fueling or engine performance. It is ONLY an emissions warning as I understand it.

BTW2, I would call that the "downstream" O2 sensor on Bank 2, since exhaust flow is obviously from the head to the tailpipe and that is the 2nd O2 sensor in that stream.

2) I don't have an N54, but as I understand the O2 sensor setup on both the N52 & N54, the Pre-cat O2 sensors are the ones that trim fueling, lean/vs rich, and the Post-cat O2 sensors are only monitoring cat function (NOT affecting fueling).

So, if you have any performance issues remaining AFTER the injector replacement, I would check elsewhere than the Post-cat O2 Sensors. If either you cannot CLEAR the P2272 connecting to the DME with any generic scan tool, or it returns, then inspect and test the wiring and connectors between the sensor and DME. Here is circuit diagram:
https://www.newtis.info/tisv2/a/en/...ntrol-valve-msv/exhaust-emission-system/oxygen-sensor-emissions-control/x5UZsdI

Please let us know what you find,
George

 

Follow-up 1

Many thanks to gbalthrop for the response, ideas of what to check and for the wiring diagram which I don't have.

Regarding the terminology (upstream vs. downstream), I agree with you completely. But the BMW tech I know and the terminology on the parts listings lists this o2 sensor as upstream:

Here's an link to the part: https://www.germanautosupply.com/bosch-0258017102.html
and the notes state:
Location: Pre-Catalytic Converter, Upstream, Upper, Front

I might think this was just an error on this site, but others are consistent in this reference to
"upstream".

Regarding the P2272 code and the SES light on the dashboard, yes the SES light comes on.

Yesterday, I reset the DME codes prior to leaving for work. I have to drive about 8 miles to get to the highway, and the SES light came on before hitting the highway. Checked the codes when I got to work (about a 34 mile drive) and P2272 is present.

After work, I reset the DME, no SES light on - I'm on the highway coming home within 2 miles and NO CODES/NO SES light came on for the ~26 miles on the highway - when I exited the highway, I can feel the minor hesitation and then after driving about 2 to 4 miles, the SES light on the dash comes on.

I will check all the wiring first - if that checks out, the next logical thing seems like an intake or exhaust air leak... do you agree?

Thanks again,
Todd inMA

 

...now I'm getting code P2272 indicating Bank 2, sensor 2 problems, stuck lean. So I replaced the associated O2 sensor in the upstream (post catalytic) exhaust location.

...Here's an link to the part: https://www.germanautosupply.com/bosch-0258017102.html
and the notes state:
Location: Pre-Catalytic Converter, Upstream, Upper, Front

WHAT did you wrap the extra 700 mm of Sensor cable around??? :rofl:

I'm NOT trying to give you a hard time, just wondering if you noticed that the sensor cable on your original part was supposed to be ~ 490 mm long, and the one they sent you is 1200 mm

For the moment, forget upstream/downstream.

PRE = Post: NOT!!!

They sent you the PRE-Cat O2 sensor for Bank 2, instead of the POST-Cat O2 sensor for Bank 2. NOT only are the cable lengths quite different, but the FUNCTION of the two sensors is quite different, as discussed earlier.

As you and I BOTH interpreted the Definition of P2272 (Bank 2, Sensor 2), that pertains to the O2 sensor AFTER/POST catalytic converter on Bank 2 (cylinders 4 - 6) -- that's closer to the tailpipe, NOT closer to the head.

Check ANY of the various online parts sites, such as the link below, and you will see that Bosch part #16796 is what you wanted (if in fact you needed to replace that sensor as opposed to correct a wiring fault) and what they sent you is Bosch part #17102:

https://www.autohausaz.com/catalog/...g/c/bmw/2007/1440982-335xi_e90/19-emission_system/5132-oxygen_sensor?s=d&page=1

PRE:
https://www.autohausaz.com/pn/17102

POST:
https://www.autohausaz.com/pn/16796

Bosch 17102 is NOT a fix for P2272 code in ANY event.

Since the "Generic Bosch" 'Downstream' Sensor (#15733 'Universal' $56) can be used on either bank, you might simply return the "Wrong" part they sent you and swap your old Post-cat sensors (there's only 70 mm length difference, so hopefully the shorter one you removed will "reach" the connector on the other bank). You might need to move the connector, but it's just for a short test period. See if the fault changes to the other bank (now P2271), and if so, you know the sensor itself is bad. If the P2272 returns, then you know the wiring/ connector/ circuit is the fault and NOT the sensor.

Please let us know how it ends -- assuming it does
George

 

George, hmmmm. The O2 sensor I changed IS the one with the longer grey sheathed cable for Bank 2 sensor 2 in the position in the exhaust pipes (I accessed the sensor for removal from under the car).....the Bosch part # 17102 matches what was installed in that position.

Is it possible that P2272 actually designates the O2 sensor in the position closer to the head/engine for the rear 3 cylinders (4, 5, 6) rather than the sensor in the position that I swapped out with the new sensor?

I will try swapping the sensors for Bank 2 (both with the longer cables - 1 has a gray sheath and the other has a black sheath) and see if the code moves to Bank 1 sensor 2.

Many thanks again,
Todd inMA

 

...The O2 sensor I changed IS the one with the longer grey sheathed cable for Bank 2 sensor 2 in the position in the exhaust pipes (I accessed the sensor for removal from under the car).....the Bosch part # 17102 matches what was installed in that position. Don't understand what you mean. Bank 2 Sensor 2 should be the SHORTEST cable (490mm) of any of the four. When you say "O2 sensor I changed" do you mean the new one or the old one? When you say Bosch #17102 matches what was installed" do you mean that was the part there BEFORE you replaced, and if so, how did you identify part# -- was that legible on the old part? If so, that was the wrong part to begin with.

Is it possible that P2272 actually designates the O2 sensor in the position closer to the head/engine for the rear 3 cylinders (4, 5, 6) rather than the sensor in the position that I swapped out with the new sensor? NO, not if I understand your question correctly. P2272 relates to the POST-cat Bank 2, or REARMOST O2 sensor of the four (that is why it has the shortest cable, as ALL cables run to the rear or center, rather than to the front (see explanation below); that P2272 code relates to the rearmost sensor (#2) on the rearmost exhaust manifold (Bank 2, cylinders 4 - 6)

I will try swapping the sensors for Bank 2 (both with the longer cables - 1 has a gray sheath and the other has a black sheath) and see if the code moves to Bank 1 sensor 2. The POST-cat O2 sensors BOTH SHOULD have SHORTER cables, 490mm & 560mm respectively, as compared to the PRE-cat O2 sensors which have 1200 & 1400 mm cables

Hi Todd,

We may be misunderstanding each other. Please refer again to the Autohaus link I provided earlier:
https://www.autohausaz.com/catalog/...g/c/bmw/2007/1440982-335xi_e90/19-emission_system/5132-oxygen_sensor?s=d&page=1

Bank 1 is the FRONT three cylinders (closest to the front bumper), cylinders 1 - 3. Bank 2 is the REAR three cylinders, cylinders 4 - 6. Since the O2 sensor cables run to connectors BEHIND the engine, the sensors that are positioned most forward (the Pre-cat sensors) have the LONGEST cables.

Likewise, the Post-cat sensors, located farther rearward in the vehicle, have cables that run rearward, or inboard, so their cables are SHORTER. So if you had the correct Post-cat O2 sensors (that codes P2272 & P2271 pertain to) installed, they would have cables that were 490mm for Bank 2 Sensor 2 (part #16796) and 560mm for Bank 1 Sensor 2 (part #16413).

You can't tell the players without a program -- so here is the program, the TIS schematic for the O2 sensors on your 335xi that I linked in my first post to this thread:
https://www.newtis.info/tisv2/a/en/...ntrol-valve-msv/exhaust-emission-system/oxygen-sensor-emissions-control/x5UZsdI

TIS schematics are interactive, which means that if you click on any of the BLUE component ID#s, you get a list of other information related to that component. Doing this with the Schematic linked above gives the following "Installation Location" for the two Post-cat sensors:
https://www.newtis.info/tisv2/a/en/e90-335xi-lim/SBFyvYR

Finally, here is the Installation Location for the Connector (X62202) that the subject sensor cable connects to:
https://www.newtis.info/tisv2/a/en/e90-335xi-lim/SEqbvP5

The key to getting the correct concept of the relationship of the cable length to the position of the sensor is that ALL cables run rearward from the sensor to its connector, and therefore the forward (Pre-cat) sensors have the LONGEST cables.

The other concern is the FUNCTION of the Pre-cat sensors (to trim enrichment or pulse duration of the injectors) is different from the Post-cat sensors (to monitor cat function and report any catalyst failure). So cable length aside, you may NOT get proper function if you put a Pre-cat sensor in a Post-cat position and connect it to the correct connector for that sensor.

Which raises another question: Are the O2 sensors connected to the correct connectors? In other words, is the REARMOST sensor, Bank 2, Sensor 2, which I understand is the one you replaced, connected to Connector X62202? Working on your bank can cause reversal or confusion of proper spatial orientation, so check against wiring colors shown in the Schematic, namely make sure it has a Black/Green wire instead of Black/Red (the other two wires are White/Gray, and Yellow, in BOTH connectors). As you also see from the diagram, the Pre-cat connectors have FIVE (5) Active Pins, whereas the Post-cat connectors have only 3.

If the vehicle is relatively new to you, perhaps you should assume that some previous owner or person who worked on it either/both (1) installed an incorrect part and/or (2) connected it to the wrong connector.

BTW, I have never worked on a 335xi, but to conduct the test I suggested, if the connectors are the same, you don't really have to move the sensors, just swap the sensor cable connections at the connectors (if you had the original/correct sensor in each Post-cat position). If the fault remains the same (P2272) then you do NOT have a faulty sensor 'cuz the DME is now receiving swapped sensor signals (Bank 2 Sensor 2 is now reporting to DME as being Bank 1 sensor 2).

Please let us know hot it goes,
George

 

So George - Based on your latest info, I have to be looking at the wrong O2 sensors.

The pre-cat sensors with the longer cables MUST be what I'm looking at - they are physically located (looking from under the car - front of my car is currently up on ramps) under the stiffener plate (which I had to remove) and just rearward of the front drive axles.

Where are the post-cat O2 sensors physically located? (How do I find them?)

Thanks,
Todd inMA

 

...Where are the post-cat O2 sensors physically located? (How do I find them?)

On my 328xi (NO turbos, so location may differ on yours) they are AFTER/REARWARD FROM the manifold cats on either manifold, about even with the rear of the Right-Front Tire. On mine, there is NO splash shield or other thing that prevents seeing the sensors, although they are on top of the pipe and somewhat hidden as a result.

How to find: Just start at the Flange that connects the Exhaust system to the Manifold Cat pipe on either bank, and look/feel forward from that point to locate the "Post-cat" sensors. On mine, the 'most rearward' sensor is on the outboard pipe, about 4" forward of the Connector Flange (2 bolts securing the pipe flange) and directly above a frame horizontal brace.

I'm tempted to say "You can't miss it" but that MAY not be correct for N54's. :rofl:

George

 

I forgot to also say - I've owned this same car since 2012 so nothing has been done before now regarding O2 sensor swapouts since I've owned the car, and up until this problem. I wasn't getting these codes at all prior to the work on the Valve Cover Gasket; it was right after that work (DIY) that I encountered the fuel injector problem (originally in Cylinder 4). The codes associated with the fuel injector and associated misfiring all went away with the injector change (and yes, the new injector is the same index (-08) as the other 5).

Right after the injector change is when I started encountering this P2272 code with the slight hesitation and SES light coming on.

Interesting - today, before leaving for work, I reset the DME. I drove the car from home the entire way to work (34 miles) and I have no codes or SES. But I did feel minor hesitation at slower speeds prior to getting on the highway. At highway speed (65-75 mph) I feel no hesitation.

Todd inMA

 

And a little more detail for clarification:

The O2 sensor I swapped with the longer cable runs up the passenger side of the engine, is then routed behind the engine adjacent to (in front of ) the firewall in front of the driver/passenger cabin, and the cabling is secured with some other cables in cable holders, and then comes under the PCV tube and down the driver side of the engine (approximately in the center of the engine compartment) and connects to a six pin connector parallel to the fuel rail - there are 5 wires with the sensor and connector.

So this sensor and connector, based on the info you've provided, I believe must be the Pre-cat O2 sensor.

I need to find the post-cat O2 sensor for Bank 2 and check its wiring. The question is, where is that sensor and connector actually located physically, and how do I know which is bank 1 vs. bank 2?

 

Ok - I've located the post-cat O2 sensors/connectors. They were under a plastic panel that had to be moved out of the way....I found how to disconnect them but I can't seem to actually swap the connections - seems like they are keyed or something.
Is that possible?


Todd inMA

 

Any help on this complication?

I still haven't figured this out - tough with the limited space even with the car on ramps.

Does anyone have further detail on whether these post-cat O2 sensors are actually keyed so you can't cross connect them on the 2007 335xi? Internally, when disconnected, 1 has a yellow ring and the other has a green ring on the connector end that is connected to the wiring back to the O2 sensor.

The part #s to order them are different - 1 PN for the Bank1 and a different PN for the Bank2 O2 sensor.

Thanks,
Todd inMA

 

Final solution - I cleaned the O2 sensors with carb cleaner and the problem went away. My theory is that my prior problems with a bad fuel injector and the associated misfire fouled the O2 sensors. It took awhile for the "residue" to burn off. Cleaning the O2 sensors appears to have solved the problems. No more P2272 code.

I also cleaned my VANOS solenoids, also with carb cleaner.

Todd inMA
'07 335xi (now with 157k miles)

 

sorry didn't read most of the replies from other seem like they misleading u

you said that yo replace the valve cover gasket now your getting lean codes
you problem rolled the valve cover gasket and undetected air getting into engine.
common error with DIY people change valve cover gasket and the rubber doesn't stay in place and rolls over n pinches.
to check you can remove intake air box and use a smoke machine into intake system should fine smoke leaking through somewhere to find that lean fault

 

RE: VC gasket

I definitely was very careful and checked this with a mirror all the way around the gasket before I tightened the bolts on the Valve cover, but I will double check this again.

Thanks for the insight and pointer.

Todd inMA