Hello. I got a 3117-001 code about a week after changing old K&N filters with the new set (same brand). Code description is: "Check component Mass air flow sensor. Right Offset drift." Engine runs fine. Fuel economy did not change.
Troubleshooting steps I took so far: Visually inspected the right filter and both sensors. Cleaned the sensors. Swapped the sensors from left to right. Installed spare sensors. The CEL comes back immediately after a code erase. Component test does not reveal that anything is wrong with the sensors.
What else can anyone recommend I do?
Thank you.

 

The best thing you can do is start fresh with new sensors and anything but K&N filters.

 

too right, paper Mann filters are what the ecu is calibrated to suck through. Not heavy K&N which even if lightly oiled will ruin every sensor downstream of it.

if you have a proper Das like scan tool you can perhaps try an air filter adaptation and see if this can be recovered without swapping map, mass meter and air temp sensors.

 

I did try new filter adaptation. I also used K&N for about 9 years without a single issue.

 

OEM filters is what I was thinking to do next.

 

New filters did not make a difference. Moving on to installing new sensors.

 

The issue was resolved by performing two steps. Installed old/spare sensors and resetting HFM drift compensation. I have a suspicion that there is nothing wrong with my sensors and I just needed to to reset both, filters and HFM. Once I verify my theory I will update this thread.

 

It’s more than a theory at this point - it’s what the WiS manual says… Every time you change an air filter you do an ME9.7 (iirc) intake adaptation to recalibrate the sensors to the new pressure map caused by a clean filter. The ECU automatically adapts and scales for changing pressure map as the filters clog and become more restrictive. Now all of that is out the window if the sensors are even lightly fouled by oil contained in a K&N filter and passed through the downstream components. Hopefully this is not the case!

 

I performed two adaptation reset procedures using my STAR diagnostics software. Not at the same time. When I installed new filters, I did the reset/calibration for that. This one I did couple of times and that is for when filters get dirty and become more restrictive. And another one is HFM drift compensation reset. I performed this when I installed different sensors. I'm not sure what ME9.7 entails but I don't think HFM drift compensation is included in that, but I could be wrong. As far as K&N and oil on filters, I think during my 10year/200k mile journey I would know by now that those filters would cause issues.

I also just found this: https://workshop-manuals.com/mercede...s_set/page_89/

 

OK. Now that the diesel cat is out of the bag, disregard everything I said. Your turbos are slinging enough oil around in that intake piping and the EGR is adding to that so much heat to create coke that a lightly oiled K&N filter amounts to a mouse fart in a storm of badness.

you don’t have a way to interrogate 9.7 Motor Electronics, because compression ignition.