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Hi I getting a couple of intermittent P Codes.
1 P221401 - 02 sensor signal biased / stuck lean bank 2 sensor 3
2 P221401 NOx sensor circuit range / performance bank 2
I attained these codes using my icarsoft MB V1.0 scanner. I don't know if it's relevant but the codes have only appeared since using E10 fuel that is now used in the UK.
Any thoughts.
Last edited by Bay Leaf; Apr 28, 2022 at 06:58 AM.
Reason: Double post
Hi I getting a couple of intermittent P Codes.
1 P221401 - 02 sensor signal biased / stuck lean bank 2 sensor 3
2 P221401 NOx sensor circuit range / performance bank 2
I attained these codes using my icarsoft MB V1.0 scanner. I don't know if it's relevant but the codes have only appeared since using E10 fuel that is now used in the UK.
Any thoughts.
Yes but they didn't come back right away. The other day I put about 25ltrs of E5 fuel in and went for a run and gave it a couple of good blasts and they didn't come back on.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
E10 is almost the only thing you can get here in the US (or at least where I live) and I have never had those codes. But, if you suddenly go from E0 to E10, maybe that could cause those. I'm guessing your car is non-turbo, like my C350. You could also check your fuel trims (long term) to see if you are actually running lean.
Yes but they didn't come back right away. The other day I put about 25ltrs of E5 fuel in and went for a run and gave it a couple of good blasts and they didn't come back on.
How many miles on your car?
Also (Just in case) be sure to check the cam sensors for oil ingress in the wiring harness. Oil can pool at the O2 sensor/connector if it is indeed leaking.
E10 is almost the only thing you can get here in the US (or at least where I live) and I have never had those codes. But, if you suddenly go from E0 to E10, maybe that could cause those. I'm guessing your car is non-turbo, like my C350. You could also check your fuel trims (long term) to see if you are actually running lean.
Yes my car is non turbo. If it was to be running lean on a particular cylinder, how could that be rectified .
How many miles on your car?
Also (Just in case) be sure to check the cam sensors for oil ingress in the wiring harness. Oil can pool at the O2 sensor/connector if it is indeed leaking.
The car has 40k on the clock, and I have recently changed all 4 cam shaft position sensors, because I'd read about the oil problem.
I removed the intake manifold in order to get access to a couple of the cam shaft sensors. But if I'm not mistaken the I had the codes appear before then. As I said they are intermittent.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
A true lean condition means too much air or too little fuel to keep the air/fuel mixture within range of the stoichiometric level . The usual culprit is unmetered air getting into the intake manifold or cylinders, meaning you have a leak somewhere past the airflow meter (or mass air flow (MAF) sensor). But, from what I can tell, we don't have the traditional MAF. That said, you may have a vacuum leak somewhere.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
There is something called a "smoke test" where a mechanic uses a device that blows smoke into the intake and see if it comes out anywhere. You can get one on ebay or amazon if you want to try yourself.
Yes but they didn't come back right away. The other day I put about 25ltrs of E5 fuel in and went for a run and gave it a couple of good blasts and they didn't come back on.
Originally Posted by Bay Leaf
I removed the intake manifold in order to get access to a couple of the cam shaft sensors. But if I'm not mistakenthe I had the codes appear before then. As I said they are intermittent.
If you are sure you were generating these codes BEFORE you did the intake, be sure you test the O2 sensors. While your car is short of the mileage in which you would expect to see a sensor failure, they can become "dirty" for a variety of reason. The fact that the codes DID NOT return after you " went for a run and gave it a couple of good blasts" indicates it may be sensor issue. Lean condition would probably return quickly with repeatability. Without XENTRY, it's a little tougher to test, but none the less relatively easy to test them. Sometimes you can clean them instead of replacing. Not saying it's not a lean condition due to an other issue, but O2 "false lean" sensor issues are pretty common and you should be aware it's a possibility when doing your due diligence.
Good Luck.
Last edited by crconsulting; May 2, 2022 at 11:49 AM.
Thank you. We went for a run out today about 110 miles although I didn't go over the UK speed limit 70 mph, the wife was with me But no engine light on and therefore no codes. I probably should have mentioned this before but when the engine light does come on it makes no difference to the performance eg not going int o limp mode.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Originally Posted by Bay Leaf
Thank you. We went for a run out today about 110 miles although I didn't go over the UK speed limit 70 mph, the wife was with me But no engine light on and therefore no codes. I probably should have mentioned this before but when the engine light does come on it makes no difference to the performance eg not going int o limp mode.
Don't know if you told us, but do you have a Mercedes supported OBD scanner? (If you don't want to go with Xentry or iCarsoft, BlueDriver and Carly are good ones, as well. They will scan all of your car's modules.)
Just because there is no CEL/MIL doesn't mean you don't have any codes. Some emissions-related codes don't trigger a light based on mileage, but rather the number of stop and starts of an engine. However, having said that, you probably don't have any codes.
UPDATE: Besides XENTRY, the LAUNCH Creader Elite 2.0 BENZ is probably the best affordable diagnostic Mercedes scanner. XENTRY really isn't a portable solution, though.
Last edited by JettaRed; Apr 19, 2025 at 09:08 AM.
As an add on to this thread I've replaced my MB V1.0 for a MB V2.0 I'm still getting the intermittent fault but it now says left hand bank Nox sensor general wiring fault with still no effect on performance.
Removed air box the other day to check filter. I noticed a small amount of oil residue around the intake, so I cleaned it off with carb cleaner spray. Also, the edge of the filter nearest the intake was dirty . At this point I will ad that the filter was a Febi that has a kind of for the want of a better word woolen type pre filter, so I turned the filter round so the slightly dirty bit was at the other end of the air box. I also sprayed the air flow sensor whilst doing the intake. Since then I have been on some good runs with the car and the warning light has not come back on.
Ok I have realised that the engine light doesn't come on after the reset but after stopping and re starting the engine. I have scanned it many times and get the same fault i.e. NOx sensor bank 2 general wiring fault. When delving deeper into it the sensor is not operational. speaking to a Mercedes independent this seems to be a common fault with the petrol engine and he advised me to have the NOx sensors remapped out. So that's the rout I'm going down. I will post in a couple of weeks when said process has been done, hopefully with good news.
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But no engine light on and therefore no codes. I probably should have mentioned this before but when the engine light does come on it makes no difference to the performance eg not going int o limp mode.
