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Is the problem reported by these trouble codes serious?
The car is Mercedes S550. 2012. 148K KM (92K M). Automatic. 4Matic.
I put in premium gas from a place that sells cheaper gas than the market. Second time I did that. The tank only had a quarter left when I filled it at this place (so I put in 3 quarters worth of gas tank). Within a couple of hours of putting in the gas and after driving about 150 KM (93 M) at highway speeds, engine light came on. I turned around and came back home (driving another ~150 KM on my way back to home). Did not notice any hiccups, noises, or erratic behaviour in the car. Hooked it up to my code scanner, and it showed the following two codes. I tried clearing DTC codes using the scanner, but they kept coming back right away.
It may be a coincidence but since it happened right after I put in gas from this location, I wonder if it is simply due to something anomalous with that gas, and these codes will go away by themselves after I put in gas from a reputable (and expensive!) place after I am low on gas again.
Please advise if these trouble codes signal some serious problem. Thanks!!!
Code 1: P209700 The mixture is too rich downstream of the catalytic converter (Cylinder bank 1)
Code 2: B210D00 Undervoltage at terminal 30
turns out the front Pre-CAT ones are posh wideband AFR sensors (needed for much later emission stds than the car was built with... ) BM bikes which run behind the car emission stds only got these later better sensors in 2016 and are about $75 each for aftermarket (with one per bank pf cylcs)
the rear Post-CAT sensors (making 4 in total) are conventional cheap ones often a little heater circuit inside gives up at 12 to 15 years - the heating allows them to be a faster responding sensor - but it job is only to inform the car how the CATs are coping with life....
The first error message says the mixture is too rich downstream of the catalytic converter. Does that sound like a O2 sensor failure/malfunction? Is it possible that O2 sensor(s) are working fine and the "rich mixture" is due to another problem?
gas is gas
a liquid is not a gas
the word you want is petrol
but using sensible words its not allowed in one country in the world
likely the main 02 sensors are worn out - the job of the rear sensors is to tell you the CAT isn't coping often as the pre VAT sensor is dead
Uh, I hope we can all appreciate that some countries say biscuits and some call them cookies.... Yes, in the US we call it gasoline or diesel or ethanol, while in Germany it might be called benzin, and elsewhere petro when using commonwealth english. I cant remember where youre located but stupidity is everywhere especially in the land of Commonwealth English. I happen to work in a science field and when referring to a gas as you are describing it would be called by its name, such as nitrogen, carbon dioxide, oxygen. We also say aluminum instead of aluminium....oh the shame.I think England may win though when their word for passing gas (fart) is "Trump". But hey a trumpet is what you put your lips to so what was going on at their Trump parties?
But since you definitely knew what I meant, as did the reader, Im surprised you just wanted to take a dig at my country of origin vs shady stolen fuel Hopefully this was enough sensible words.
2007 S600, 2007 Chrysler 300 SRT8, 2000 C5 Corvette, 2017 Mustang GT, 2023 300C, and a 2019 Lincoln
Never say never. But given your mileage and year, the O2 sensor probably just failed coincidentally. If you thought it was bad gasoline, and it could be; you could try a 20 ounce bottle of Techron fuel system cleaner (my V12 S600 uses it every other month to keep a CEL light off). I doubt an additive will repair a bad O2 sensor, but on the off chance you sucked up gasoline contaminants, you would see an improvement.
The problem with running with a bad O2 sensor and a rich condition is killing your catalytic converter and also washing the pistons of oil. If a bottle of fuel additive does not have any significant impact (and it is a long shot), get a new O2 sensor installed. And don't buy gasoline at that fuel stop anymore.
the car having a low volt warning is very common, they consume so many amps an older battery, or key left on for a few minutes will get them popping up everywhere...
you can almost delete pointless codes every week you'll find something on these cars... most are worrisome nothingness - Yes they have very advanced diagnostics and yes BOTH front and rear SAMs can be updated to get even more diagnostic info (alongside other modules but those are the key ones). Occasionally it can be useful
go a bit deeper and likely the tool you have will start to give more info about what the issue it... its often best to kill any error you find - drive for ten mins connect a charger and scan again and see what was real...
most CAT sensors can just give up anywhere over 10 years - they have a tough life getting cooked - mileage often has nothing to do with it
Uh, I hope we can all appreciate that some countries say biscuits and some call them cookies.... Yes, in the US we call it gasoline or diesel or ethanol, while in Germany it might be called benzin, and elsewhere petro when using commonwealth english. I cant remember where youre located but stupidity is everywhere especially in the land of Commonwealth English. I happen to work in a science field and when referring to a gas as you are describing it would be called by its name, such as nitrogen, carbon dioxide, oxygen. We also say aluminum instead of aluminium....oh the shame.I think England may win though when their word for passing gas (fart) is "Trump". But hey a trumpet is what you put your lips to so what was going on at their Trump parties?
But since you definitely knew what I meant, as did the reader, Im surprised you just wanted to take a dig at my country of origin vs shady stolen fuel Hopefully this was enough sensible words.
I will chime in with my usual advice on these vehicles...just replace all four O2 sensors, and see what you have after clearing codes. Like every other part, they are nearing 20 years old. They will all need replacing anyway eventually, so you might as well start there. O2 sensors aren't expensive...mine were like $300 for good quality ones at Rock Auto.
Thanks very much for the tips and advice. Will try all of those. I was also thinking of getting the fuel out somehow, and refilling it from tier-1 place like Shell, where I usually go.
the car having a low volt warning is very common, they consume so many amps an older battery, or key left on for a few minutes will get them popping up everywhere...
you can almost delete pointless codes every week you'll find something on these cars... most are worrisome nothingness - Yes they have very advanced diagnostics and yes BOTH front and rear SAMs can be updated to get even more diagnostic info (alongside other modules but those are the key ones). Occasionally it can be useful
go a bit deeper and likely the tool you have will start to give more info about what the issue it... its often best to kill any error you find - drive for ten mins connect a charger and scan again and see what was real...
most CAT sensors can just give up anywhere over 10 years - they have a tough life getting cooked - mileage often has nothing to do with it
I will chime in with my usual advice on these vehicles...just replace all four O2 sensors, and see what you have after clearing codes. Like every other part, they are nearing 20 years old. They will all need replacing anyway eventually, so you might as well start there. O2 sensors aren't expensive...mine were like $300 for good quality ones at Rock Auto.
That sounds like a good way to go. Replace them all, rather than piece meal every few months at this time. Thanks.
Rock Auto charges a hefty shipping fee up to a certain wait/volume. Anything else that might be getting ready to quit at this age (i,.e., most common to go on these vehicles at around this age), which I can proactively order and replace to make the most use of Rock Auto's shipping?
Never say never. But given your mileage and year, the O2 sensor probably just failed coincidentally. If you thought it was bad gasoline, and it could be; you could try a 20 ounce bottle of Techron fuel system cleaner (my V12 S600 uses it every other month to keep a CEL light off). I doubt an additive will repair a bad O2 sensor, but on the off chance you sucked up gasoline contaminants, you would see an improvement.
The problem with running with a bad O2 sensor and a rich condition is killing your catalytic converter and also washing the pistons of oil. If a bottle of fuel additive does not have any significant impact (and it is a long shot), get a new O2 sensor installed. And don't buy gasoline at that fuel stop anymore.
Keep us posted.
Thanks very much for the tips and advice. Will try all of those. I was also thinking of getting the fuel out somehow, and refilling it from tier-1 place like Shell, where I usually go.
Never say never. But given your mileage and year, the O2 sensor probably just failed coincidentally. If you thought it was bad gasoline, and it could be; you could try a 20 ounce bottle of Techron fuel system cleaner (my V12 S600 uses it every other month to keep a CEL light off). I doubt an additive will repair a bad O2 sensor, but on the off chance you sucked up gasoline contaminants, you would see an improvement.
The problem with running with a bad O2 sensor and a rich condition is killing your catalytic converter and also washing the pistons of oil. If a bottle of fuel additive does not have any significant impact (and it is a long shot), get a new O2 sensor installed. And don't buy gasoline at that fuel stop anymore.
Keep us posted.
I am just trying to wrap my head around this problem and its causes.
I understand the risk of running with a bad O2 sensor and rich condition. The question I have is that is the rich condition caused by bad O2 sensor, or a bad O2 sensor could be erroneously reporting rich condition? And as a follow up, if the O2 sensor is replaced and rich condition error code remains, what could be causing rich condition?
Does this error indicate which O2 sensor might have failed? Downstream? Upstream?
This car has 2 sensors upstream, and 2 sensors downstream. I would have to replace both in the appropriate stream location, right?
You are asking the wrong questions. The P2097 error does not mean that any O₂ sensors are bad, it's just a starting point for further analysis.
Get your scanner and start doing proper diagnostics, as mentioned above.
Also read https://forums.mbclub.co.uk/threads/p2097-error.285825/
That sounds like a good way to go. Replace them all, rather than piece meal every few months at this time. Thanks.
Rock Auto charges a hefty shipping fee up to a certain wait/volume. Anything else that might be getting ready to quit at this age (i,.e., most common to go on these vehicles at around this age), which I can proactively order and replace to make the most use of Rock Auto's shipping?
Yes, Rock Auto shipping is complicated. Since they ship from a bunch of different places, you have to 'game' their system in order not to be hit for shipping on each item. Use trial and error building your cart of stuff...like maybe a Denso O2 sensor comes from Warehouse A with all your other stuff, but a Bosch oil filter comes from Warehouse B. Find a different filter or whatever that comes from A. The list is long of stuff you could/should change. Control arms, sensors of all varieties, ignition components, brake components, fluids, etc. I asked AI a few days back what to change to make the car 'as new as possible'. It listed off like 30 things, but I'd already done 29 of them. You could do the same asking AI using your vehicles particulars. If you really want to remove the gas, the tank can be accessed from under the rear seats. Pump out and use it in your lawn mower or chain saw.
Yes, Rock Auto shipping is complicated. Since they ship from a bunch of different places, you have to 'game' their system in order not to be hit for shipping on each item. Use trial and error building your cart of stuff...like maybe a Denso O2 sensor comes from Warehouse A with all your other stuff, but a Bosch oil filter comes from Warehouse B. Find a different filter or whatever that comes from A. The list is long of stuff you could/should change. Control arms, sensors of all varieties, ignition components, brake components, fluids, etc. I asked AI a few days back what to change to make the car 'as new as possible'. It listed off like 30 things, but I'd already done 29 of them. You could do the same asking AI using your vehicles particulars. If you really want to remove the gas, the tank can be accessed from under the rear seats. Pump out and use it in your lawn mower or chain saw.
You are asking the wrong questions. The P2097 error does not mean that any O₂ sensors are bad, it's just a starting point for further analysis.
Get your scanner and start doing proper diagnostics, as mentioned above.
Also read https://forums.mbclub.co.uk/threads/p2097-error.285825/
I really appreciate this note. It sets me in the right direction. As you can easily tell, my tech knowledge about these things is very low. I am doing this knowledge gathering to arm myself as a protection against a potential massive bill and a load of BS from the mechanic or stealership I would go to have this fix.
Thanks!
You are asking the wrong questions. The P2097 error does not mean that any O₂ sensors are bad, it's just a starting point for further analysis.
Get your scanner and start doing proper diagnostics, as mentioned above.
Also read https://forums.mbclub.co.uk/threads/p2097-error.285825/
Hello again. I just read all the replies again and pretty much all of them are suggesting that O2 sensors have likely gone bad, and I should just replace them. If I am missing the point (or some clue) to use my scanner to do further diagnostics, please point me in that direction. I will really appreciate that! Thanks.
To test the sensors, look at the live data of the 4 O₂ sensors when the engine is warm and running (closed loop).
The values of the pre-cats should jump up and down rapidly, the post-cats should be steady (and have rougly the same value)
it says the Post CAT bank 1 sensor is indicating its running rich - its job is ONLY to flag the status of the exhaust gases post CAT - it doesn't control the fuel mixture - thats the job of the Pre CAT sensor
the car thinks is running rich - in which case the Pre CAT one that side ought to be flagging an issue OR the CAT is not doing its job OR the sensor itself is playing up - they usual fail indication its heater circuit has dies - but its not the only fault it can have... replacing that offending sensor could be the cheapest way to check - as you can faff finding someone to help and playing silly buggers checking wiring and running various diagnostic voltages etc. - or for half the time and effort swap it out and see where you are
these simple ones can come from aliexpress for as little as $16 and in today's world are likely better made than Bosch designed to fail junk
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Hopefully this was enough sensible words.
