P11C7 code from a gasoline engine?

Maintenance/Repairs
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1

2019 BMW X1 with a B46A engine
CEL illuminated and a generic OBD II reader reports code P11C7, and defines that as a fault with the NOx sensor circuit.
Wait, what? My understanding is that NOx sensors are used only in diesel emissions fluid injection systems. Why would we get that code from a gasoline engine?
BMW-specific code lists that I have found don’t even list this as a valid code for a US market BMW.
The CEL comes and goes, generally corresponding to cold wet weather, which suggests a possible wiring problem somewhere.
I don’t even know where to start to diagnose this. Anyone seen a similar problem?

Thanks!

2

Because gasoline engines also produce NOx emissions.

That’s the purpose of the EGR system.

To reduce NOx.

Tester

1 Like
3

Thanks for the response.

Of course, gasoline engines create NOx, but they have no need to measure it directly.

Just to be certain, I went to the RealOEM part # website and checked. I found no NOx sensor for this vehicle. Also, when I Google BMW NOx sensor, they are listed only for diesel BMWs.

4

I think the software in your code reader is outdated, try a different scan tool.

5

Thanks for the tip. I will try my code reader (recently flash updated) and report back. May be a while, as this is a relative’s car and is 180 miles away.

6

Concur w/Nevada above, most likely explanation is problematic scan tool. May require a visit to a BMW specialist shop to obtain the correct diagnostic code.

7

I always try to follow-up posts in case anyone is interested.

The code is still a mystery.

My 2018 vintage Foxwell scanner gave the same code in OBD II mode, and refused to read the VIN from the 2019 X1 when in BMW mode. I keyed in the VIN and the scanner said it was invalid.

I dug in and found that the firmware had actually not recently updated and the most recent firmware on the Foxwell website was 2018… I wrote to Foxwell asking when I might expect updated firmware. They responded that this is an old model (it was the latest model four years ago!) and there would be no more firmware updates for it. They said I should buy a new scanner.

I may buy a new scanner, but it won’t be a Foxwell.

As for the car - it runs fine and does not need to pass SMOG inspection for four more years, so they may take it to a BMW shop, or they may monitor the internet waiting for some other X1 owner to have the same mysterious code and post the solution.

8

I can’t find a reference to that code number. But it may well be your car – even though a gasoline engine – still uses an NOX sensor. Google NOX sensor gasoline engine. Uncommon, but may have something to do with your engine being a turbo, higher combustion temperatures produce more NOX. Assuming your car doesn’t use the diesel-urea technique, presumably there is something the car’s drivetrain computer can do to mitigate NOX exhaust , if it determines there too much NOX out the tailpipe for the driving situation. For example may be possible to store it, and clean it later when driving situation is not as extreme.

9

If you give me the last seven digits of your vin number I can check for you ( some petrols are fitted with them)

10

3H34306
Thanks for checking!

11

Had a look on the Bmw system, definitely no Nox system on your vehicle. Can’t see any specific service solutions on the fault but there are a few regarding spurious fault codes related to emissions, some appear when the next oil change is coming up especially if the car does short trips, there’s a software update for the DME to rectify this. Hope that’s helpful.

12

Thank you!

1 Like
13

This an old thread, but I always find it satisfying when threads I follow post the ultimate resolution.

I did not mention it because I did not think it was related, but the same time the bogus P-code appeared, the i-Drive reported a failure in the SOS telephone system. The code indicated a failed battery. The battery is above the headliner and is a PITA to get to.

The car was taken to the dealer last week. The dealer was vague about what they did, just saying that they reflashed some firmware in accordance with a recall. They also replaced the failed battery. Cost $0

Surprising that it would trigger a P-code, but recall NHTSA ID Number: 10218420 was to resolve a firmware problem in the SOS phone (telematics system) that would not let it link to 4G or 5G cell towers. I theorize that the rechargeable battery failed prematurely because it went dead searching for a 3G cell tower it could link to every time the car was shut off.

No more codes of any kind now.

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14

Thanks for the update, always good to hear the outcome :+1:. There’s been a few TCB battery failures but I’ve never seen one cause that code before.