cabby850

HI,

I have a 97 E420 and the next day after I installed a K&N air Filter my check engine light came on. I tried to replace it with the stock air filter and disconnecting the battery to see if the check engine light will go away. After 10 min, the check engine light still came back on. I had AutoZone did a read out of the check engine light and it showed this:

P0136 O2 Sensor Circuit Malfunction (Bank 1 Sensor 2)

Is this just a coincidence that my O2 sensor died the next day or did the K&N air filter ruined my O2 sensor?

Does anyone know exactly which O2 sensor do I need to replace?
Can I just replace one or do I have to do it in pairs?

Thanks for your help.

Ed

jimmydagreek

I am also curious about this as I also want to replace my air filter and housing and do not want to have any problems. Anyone knowledgeable, please advise. Thanks...

Turbo][

Is that the only P-Code it read? Bank 1 and Sensor 2 is the passenger side after TWC O2 sensor. this sensor is usually to check how well your TWC is working. I would have them reset the code, and run the car with your stock air filter for a few days, and see if it comes back on. If it doesn't, run the K&N filter again. If the MIL comes back on, you might need to replace both the TWC and/or the O2 sensor.

If you are handy, the voltage level of the downstream O2 is 550mV at 80C degrees at idle. It will flexuate, but should be within that value.

trustz

Hi guys

I have my 97 E420 with K&N filter for 2 years without any problem,NO check engine light at all, now I have the HKS Power flow intake system and still No problem at all ! Its your O2 sensor !









Trustz

jimmydagreek

Hey trustz, got any pics. of your intake system, and of your ride of course???

MARK CUMMINS

I Have Used K/N Filters for Several Years Without any Problems!
If You Over oil the Filter you will Take out the MAS !
I Also have a Custom Intake on my W210 (Carbon Canister) and Dont have any Problems with the CE lite...The O2 sensors do Go bad!

E-Klasse

I have had a K&N filter in for a couple of years too with no fault codes generated. I would think it would affect the MAF sensor most of all. I have heard of people re-oiling their K&N or installing it wrong and getting oil in the MAF. It sounds like your O2 sensor just went bad with out the fault of the K&N.

cabby850

Hi Turbo][,

Can you please explain what is TWC? Is it possible that a K&N air filter do harm to O2 sensor? whats the connection between K&N air filter and O2 sensor? I didn't overoil the filter as it was brand new. Is it just an coincedence that the check engine light came on the next day I installed the K&N? because I know other people have been using K&N air filter in their mercedes without any problem.

THanks

Ed

Turbo][

TWC=Three Way Catalytic.

O2 sensors are PRONE to go bad. All it takes is some dirt or a over heated engine. However usually its Sensor 1 that goes bad...hardly the trailing (downstream) Sensor 2. If sensor 2 is bad, the cause of it is a failing TWC.

The only way to verify if the O2 is bad or not is to take a measurement. All you need is a multimeter. Since Narrowband O2 only reads up to 1v. If you get no reading, that means it dead...and if the reading is way above 1v its bad...

IF you don't know how or unable to do this yourself, you'll probably have to take it to a mechanic...but at least you know what could be the problem, and not get "jacked" on something that isn't the problem.

MB Life

where are the O2 sensors located?
Are they easy to get to?
How much are the replacement parts? (approximately)

Thanks

Turbo][

The upstream O2 is located on each bank about 6-8" from the end of the exhaust manifold.

The downstream O2 is located on each bank about 4-6" from the catalytic converter.

The downstream are much more easier to get to. The O2 are toqued in pretty good. I think it has about 50-80nm on them. I can verify if you really want to know

As for prices. If you can do it yourself, you can SAVE A LOT on labor, because ppl seems to like to charge alot on changing O2. But for MB OEM O2 they run from $150-$200, depending where you get it from.

I have read you can use other O2....but you will have to splice the wires and do a custom wiring job

MB Life

Turbo II

Thanks for the info.
I have a 96 E320. This is a straight 6 engine so I am not sure if it is different than what you explained.

Please let me know what you can. I would like to replace the sensors myself. I have been doing most of the maintenance on this car.

Thanks again.

Turbo][

Ah..okay. For the inline its the same, of course you only have one bank. ALL 96+ car must be OBDII. So you will have 2 O2 sensors. One before and after the catalytic.

cabby850

Turbo][,


you mentioned the O2 sensor that I need to replace is the passenger side after the TWC. The Mercedes Parts Dept quoted me $188 for it while Auto Zone quoted me like around $100 for a Bosch O2 sensor. Is the Bosch O2 sensor the same as the original Mercedes O2 sensor?

I also found this site that sells O2 sensor but I am confused which one I should get, would you please help me to pick the right one?

http://catalog.mercedes-parts-online...=1997&x=23&y=9

I don't know which chasis number my car belong to and I don't want to buy the wrong one.

Thanks for your help.

Edward

Turbo][

I am not sure. The benz uses a 4-pin plug. Just make sure it's something like that.

rp718

My K&N (really the oil) took out my MAS last Friday.
Too bad you can't run the K&N dry.

BlownV8

These cars go through MAF's very quickly. The MAF's are total junk and usually only last for around 60,000 miles. I've had a K&N in my E55 for around 8 months and 20,000 miles with no issues. My MAF went out with a stock filter....it just happens and is probably unrelated to the K&N unless the wrong side was oiled. The part is a Mass Air Flow meter. You go to MASs on Sunday's.