W212 E63 AMG S - Recurring Check Engine code (Oxygen sensor)

[TrueSpirit]

Hi all
not sure if anyone else has been having a similar issue on their W212 E63s. this is the third time i've had an engine oxygen sensor code (lambda sensor i think) come up (via an engine warning light). Took it to the indy after the first time it happened and they said it was a stored code and probably a one off. Given it has happened twice more times now (most recently when "efficiently" merging onto the motorway with a fully warmed up engine and a hundred+ miles into my drive on the day), i'll be taking it in to get something done / have the sensor replaced. seems like in every instance i was well into a long drive, put my foot down and the light appeared.
The second time, i called my breakdown provider and the funniest thing happened, the guy who came to look at the car actually has a w212 e63 estate, i went to his house after he checked and cleared the code to admire his lovely car (i much prefer the estate to the saloon so was very jealous of his beautiful car), he had about 5 cars including a subaru impreza, old porsche cayenne etc.

Third time happened on saturday when i was driving back from Liverpool , oddly the code just disappeared when i started the car up this morning.

wondering if anyone else has experienced these annoying codes ?

 

[alexanderfoti]

What is the code and definition?

 

[TrueSpirit]

I had a pic, lost it. The stored codes are gone too. It's a lambda sensor code. Oxygen sensor. It'll cost me 300 squid to replace it or at least check the connection , see it needs cleaning etc. Bit disappointed as it goes out of my exhaust mod pot and I want an exhaust with flaps I can control which means dropping £££££££

 

[alexanderfoti]

There are probably 20 different variations of O2 sensor codes. Mixture too reach, sensor too slow, sensor short to ground, sensor open circuit etc etc. Hard to predict the root cause without this unfortunately.

 

[ALFAitalia]

I had a very similar issue to the OP.....replaced the sensor....fine for a week them the code was back. Turned out to be heat damage to the wiring. Inserted a new section....been good since. Intermittent faults on O2 sensors are often the wiring or connectors as the sensors are a bit like light bulbs....no half way house...they work or they dont.....in most cases at least!!!

 

[TrueSpirit]

There are probably 20 different variations of O2 sensor codes. Mixture too reach, sensor too slow, sensor short to ground, sensor open circuit etc etc. Hard to predict the root cause without this unfortunately.

Agreed, I'm a bit disappointed I can't find the picture I took. If I manage to cause it again I'll gather all relevant evidence.
It isn't a big issue at all it seems luckily

 

[TrueSpirit]

I had a very similar issue to the OP.....replaced the sensor....fine for a week them the code was back. Turned out to be heat damage to the wiring. Inserted a new section....been good since. Intermittent faults on O2 sensors are often the wiring or connectors as the sensors are a bit like light bulbs....no half way house...they work or they dont.....in most cases at least!!!

I'll mention this to DDR actually. The wiring of the sensor itself or the bit it connects to can you remember?

 

[ALFAitalia]

In my case it was the wiring between the sensor and the plug......just to be clear this was an A Class (also had the same problem on my ALFA).....but an O2 sensor is an O2 sensor!!

 

[ant1]

Sell car to me, problem solved

 

[TrueSpirit]

So after a 1k+ mile tour to Scotland, on the way back I got the usual check engine light and downloaded the codes,

I also did further analysis and one sensor's voltage is all over the place, fluctuating continuously between 0.2v to 0.5v
Here's the naughty one:


Here's the well behaved one which was reading constantly at 0.735v:



CONCLUSION
I think i have nailed the culprit. Not sure i want to replace it anytime soon as my garage queen (bmw 645ci) is showing what fine catch they(dont want to assume gender, that would be very transmission phobic, especially it is an auto but it generally prefers to be driven in manual mode - see ) , constantly bleeding me dry and hardly giving me any smiles per GBP spent. Yes it sucks, but only the funds from my wallet. Currently i can floor the accelerator pedal and it goes nowhere fast so off to the garage to replace the rusty brake lines and also now probably a MAF meaning i cant take it on the wales road trip either in a couple weeks meaning my e class will have had another 1k plus miles packed on within the space of 3 weeks following my 1.3k mile weekend scotland trip. That'll teach me to get tangled with a old BMW (Bitchy + Moneygrabbing Whore),

 

[alexanderfoti]

Code is for B1S1 actual value is for B1S2 post cat. Post cat is narrow and and should fluctuate slightly up and down. Pre cat is wide and and should only change. Very slightly at idle etc.

 

[TrueSpirit]

Code is for B1S1 actual value is for B1S2 post cat. Post cat is narrow and and should fluctuate slightly up and down. Pre cat is wide and and should only change. Very slightly at idle etc.

Thanks! agreed, my reader doesnt give me any voltage value for B1 S1 unfortunately but there's quite a big difference between B2S2 which is very stable and B1S2 readings, no idea if normal etc unless i do some reading up on this.

One other variance of note is below (0.8% fuel trim on B1 Sec sensor):


not sure if this variance means anything at all. any ideas @alexanderfoti

 

[alexanderfoti]

You need to sanity check that the readings are not actual fueling issues on that bank, air leaks etc?

 

[TrueSpirit]

Thanks, i'll have to take it to someone who knows what they're doing, it is out of my area of competence for sure.

 

[Uky]

I had a similar problem with my C207, V6, E350 Petrol. Fluctuating O2 sensor readings. We suspected either sensors or the air mass meter but before attempting to replace anything, a friend said "Stop! I think I know the cause: Check the crank case ventillation hose. On one specific location, there is a Y-joint. One path goes to the air mass meter, the other (if I am not wrong) to the carbon cannister) The Y-joint cracks with time. The crack is not visible from above but lift this rubber hose up and you can see the cract facing the engine metal. On the V6, this crack normally appears after > 100.000 kms.

Sure enough: There was a crack. It was possible to repair it temporarily and then ordering a new hose. Less than € 20.

After replacing this, sensor readings went back to normal. DTC's was cleared and did not reappear.