CEL code overload?
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Joined: Mar 2019
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C300
CEL code overload?
Hi forum members, I am new to the forum and to Mercedes so I will be needing some solid mechanical advice. I hope I am posting in the correct forum for help. I don’t actually own a Mercedes, I am here on behalf of my son in-law who owns a 2011 C300. He has been driving with a CEL for some time and he finally asked me for advice on his car. I’m fairly knowledgeable when it comes to working on cars, but know little about the Mercedes brand. I know that one code can trigger another and on down the line, so I’ll list them all and see where everyone thinks we should go first. P0410 (air system), P2414 (02 sensor exhaust error), P2626 (02 sensor pumping current trim), last but not least P2196 (sensor signal biased/stuck). I know he should be running premium gas, but just uses 87 octane. Should we just try some heavy duty fuel system cleaner to see if that will do anything first, or is there a more serious problem? Any help would be appreciated.
Super Member
Joined: Sep 2015
Posts: 848
Likes: 87
From: Milwaukee, WI USA
2012 C300 4Matic
I would suggest having him fill up with premium fuel first. If he is using regular grade thinking he is saviong money, he is only fooling himself. He probably has reduced MPG and is possibly triggering some of those lights. Also, get a code reader and delete the codes. After running a tank of premium see what codes come back and then go from there.
Thread Starter
Newbie
Joined: Mar 2019
Posts: 5
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C300
I would suggest having him fill up with premium fuel first. If he is using regular grade thinking he is saviong money, he is only fooling himself. He probably has reduced MPG and is possibly triggering some of those lights. Also, get a code reader and delete the codes. After running a tank of premium see what codes come back and then go from there.
Super Member
Joined: Sep 2015
Posts: 848
Likes: 87
From: Milwaukee, WI USA
2012 C300 4Matic
If he would fill up with the premium fuel than any further advice woudl be useless because if he has been doing that for a while that could be the root of his issues. Are things that tight that another $3-$4 per tankful couldn't be afforded? It isn't about a couple extra miles per gallon. The engine is designed and set up to use a ceratin grade of fuel.
Seems like not every reader can erase Mercedes codes. I know my old reader would not. I got an i-carsoft brand. I am not familiar with the phone based app you mentioned. If you would do a search on here I'm sure you could find several suggestions that others are using.Once you clear the codes and see what comes back you will at least know what is current vs.what might be stored a long time and are not pertinent now.
Good luck.
Seems like not every reader can erase Mercedes codes. I know my old reader would not. I got an i-carsoft brand. I am not familiar with the phone based app you mentioned. If you would do a search on here I'm sure you could find several suggestions that others are using.Once you clear the codes and see what comes back you will at least know what is current vs.what might be stored a long time and are not pertinent now.
Good luck.
Thread Starter
Newbie
Joined: Mar 2019
Posts: 5
Likes: 0
C300
If he would fill up with the premium fuel than any further advice woudl be useless because if he has been doing that for a while that could be the root of his issues. Are things that tight that another $3-$4 per tankful couldn't be afforded? It isn't about a couple extra miles per gallon. The engine is designed and set up to use a ceratin grade of fuel.
Seems like not every reader can erase Mercedes codes. I know my old reader would not. I got an i-carsoft brand. I am not familiar with the phone based app you mentioned. If you would do a search on here I'm sure you could find several suggestions that others are using.Once you clear the codes and see what comes back you will at least know what is current vs.what might be stored a long time and are not pertinent now.
Good luck.
Seems like not every reader can erase Mercedes codes. I know my old reader would not. I got an i-carsoft brand. I am not familiar with the phone based app you mentioned. If you would do a search on here I'm sure you could find several suggestions that others are using.Once you clear the codes and see what comes back you will at least know what is current vs.what might be stored a long time and are not pertinent now.
Good luck.
Super Member
Joined: Sep 2015
Posts: 848
Likes: 87
From: Milwaukee, WI USA
2012 C300 4Matic
Great. Good luck getting the issues resolved. Hope it is simple and cheap.
Super Member
Joined: Apr 2010
Posts: 705
Likes: 55
From: LA LA Land
'08 C300 MM Pano
I am curious as to how many miles he has on his 2011?
If he is at or near 100k miles, and especially with using regular gasoline, it might be time for him to replace O2 sensors... But that will cost a pretty penny so follow Alfadude's advice by going premium and see what that does.
By the way, for codes that cannot be cleared, it will take several starting cycles for them to reset on their own. So it might take more than a single tank of premium to realize any possible changes.
If he is at or near 100k miles, and especially with using regular gasoline, it might be time for him to replace O2 sensors... But that will cost a pretty penny so follow Alfadude's advice by going premium and see what that does.
By the way, for codes that cannot be cleared, it will take several starting cycles for them to reset on their own. So it might take more than a single tank of premium to realize any possible changes.
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Thread Starter
Newbie
Joined: Mar 2019
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C300
I am curious as to how many miles he has on his 2011?
If he is at or near 100k miles, and especially with using regular gasoline, it might be time for him to replace O2 sensors... But that will cost a pretty penny so follow Alfadude's advice by going premium and see what that does.
By the way, for codes that cannot be cleared, it will take several starting cycles for them to reset on their own. So it might take more than a single tank of premium to realize any possible changes.
If he is at or near 100k miles, and especially with using regular gasoline, it might be time for him to replace O2 sensors... But that will cost a pretty penny so follow Alfadude's advice by going premium and see what that does.
By the way, for codes that cannot be cleared, it will take several starting cycles for them to reset on their own. So it might take more than a single tank of premium to realize any possible changes.
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Super Member
Joined: Apr 2010
Posts: 705
Likes: 55
From: LA LA Land
'08 C300 MM Pano
Unfortunatley he is right close to 100k. When we changed his tranny fluid last fall, he was at 89,000, so likely has 2-3000 more on it by now. How are Mercedes when it comes to using aftermarket 02 sensors? I have had good results with other cars that I used aftermarket sensors.
2 X And
2 X
Those are confirmed to be the direct OEM replacements, and they would total approximately $350 (before tax).....
And in all honesty, considering this job is only going to be done once during my ownership of this vehicle (once every 100k or so miles), I did not see much benefit in deviating from OEM...
I mean if it boils down to saving a $100 or so, and with what potential problems a faulty or incompatible sensor could cause (O2 sensor faults are in and of themselves, ones that turn out to be elusive and difficult to diagnose) the hassle might not be worth the effort to correct any issues.
I wish I had a better answer or you (regarding non-OEM)... But I don't!
Thread Starter
Newbie
Joined: Mar 2019
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C300
Okay folks, things have been slowly happening on getting them cleared up. Since I stared, one additional code kicked up. I forget the code right now, but the explanation was coolant thermostat wasn’t reading as expected. Would that indicate a new thermostat was needed?
Also we tackled the P0410 first and found that the smog pump was froze up. Replaced it along with a new fuse. The code is still present, so what next? I verified the new pump works, and there is probably a relay involved somewhere if I could only locate it. We couldn’t find a page in the owners manual that identified and labeled the fuses and relays. Where could I get that information? Also I wasn’t sure if the engine needed to be cold or if the pump comes on for every startup. He’s going to drive for a day or so and see if it goes away.
Also we tackled the P0410 first and found that the smog pump was froze up. Replaced it along with a new fuse. The code is still present, so what next? I verified the new pump works, and there is probably a relay involved somewhere if I could only locate it. We couldn’t find a page in the owners manual that identified and labeled the fuses and relays. Where could I get that information? Also I wasn’t sure if the engine needed to be cold or if the pump comes on for every startup. He’s going to drive for a day or so and see if it goes away.
