jnor4307

2001 e320
Hey guys,

Couple quick questions, for the past couple weeks my CEL was on every time I drove it. I got a OBD2 reader and it spat out P0115, P0130, P0150. With the P0130 & P0150 I read that it was unusual for both O2 sensors to go off at the same time, so I ended up cleaning my MAF today super easy even for a novice diy guy like me. Afterwards I drove locally for a few things and the CEL kept staying on I rechecked and same codes For work I drove 3hrs. At the end of this trip I had some shopping I needed to do and noticed that CEL light wasn't coming on at all!!! I put the OBD2 back in and it still spat out the same 3 codes even though the CEL was now off. I know the CEL isn't burnt out since it flashes on during starting up. So my questions...

#1) When P0130 & P0150 is it usually the MAF needing a good cleaning/replacement from your guys experience? My car has 213km bought at 170 and I don't know history if O2 every replaced. BTW after the MAF I swear that my car is running/idling better.

#2) Do I need to reset the codes, with either the OBD2 or with a "Soft reset" assuming the light stays off...or should I just do it anyways regardless. My friend told me not to since the computer will "RESET itself if you fixed the problem"

#3) I did not address the P0115 code which from what I read is either a "coolant sensor or thermostat needing to be replaced". I assume the CEL stayed off (if the other codes were fixed by my cleaning the MAF) because at the end of the trip the last couple stops I made the engine was/stayed fairly warm. However, even after 3 hrs of solid driving the temp never reached 80, from memory it was around 60's. So heres my thinking outloud....

I figure that tomorrow (here in canada northeast of edmonton) that with the low temp the CEL might come on. If it does, should I get the sensor/thermostat together or start with one or the other. I still get good heat in car when driving. And silly question, could someone point me in the direction of the DIY for the sensor if there is one? I couldn't find one and I found one for the thermostat which looks pretty straightforward.

Thanks for any feedback/help!! PS these forums have already saved me $$ with srs seat sensor and brake light switch!!!

Plutoe

Well I have some good and bad news. The good news is that you did not ruin your MAF sensor while supposed cleaning----write Santa a letter and tell him you will never do that again. Remember P0100 is the MAF fault don't touch the MAF unless you read that code and forget about the bar talk of cleaning.

The other bad news is that for your car and engine there is no fault P0150. You either transposed the numbers wrong or your girl friend was doing the reading---Oh well!

The real good news is that you did not run out and buy a O2 sensor, because most probably the fault would return-----why you say---well you do not understand your car for one----the O2 sensor works with the engine coolant temp sensor to function properly, therefore your NOT changing the engine coolant temp sensor is the reason why you have the upstream O2 sensor fault----it's looking for an 80C reading and not getting it.

And yes P0115 is the engine coolant temp sensor-----change it

The crux of this holiday message is purchase a NEW sensor. Then first read the codes and then clear the codes. Then install the coolant temp sensor.

A side bar it may take a few drive cycles to clear P0130, but if you didn't ruin it in the process the fault should not reappear. Good Luck

jnor4307

So good news... my check engine light is still off. Hasn't come back on on in 2 days. I double checked with my OBD reader the codes and found
1 fault and 2 pending once again P0155, P0130 (pending) P0150 (pending) Its a cheap autel maxiscan 300 princess auto selling right now on sale 35$ 80 reg. I thought the whole point of an OBD2 was universal readings but maybe something with the mercedes means it can't read it properly.

Few questions. Plutoe/all
#1) RE: MAF For my own benefit/knowledge, why not clean the MAF sensor? I used the crc MAF cleaner. Is there something special about the mercedes sensor that means it can be damaged with cleaning. By cleaning I don't mean touching it just spraying it. There are multiple diy posts on how to clean various models.. https://mbworld.org/forums/e-class-w...2004-e320.html

http://www.benzworld.org/forums/w210...-cleaning.html


#2) I haven't cleared any of the codes with the OBD2 reader so why is the CEL off even though it keeps finding a fault and 2 supposedly pending. Do not all faults cause a check engine light to go off?

#3) I am planning on replacing the the temp coolant sensor even w/out the CEL on unless somebody has a good reason not too. And clear codes manual per Plutoe's suggestion. Does anybody know if there's a diy post for it.

Cheers and thanks again for all the info/help/advice!
Joshua

Plutoe

Cleaning sensors if very personal and dependent upon how gullible you are to advertising.

My point is that there is a market for everything----take bull **** spray. I could put a different label on the can and call it MAF cleaner, advertise it and it will sell.

Me personally have bought bull **** spray but have never bought a can of MAF cleaner. This is America.

Before you ware yourself out over faults, take a day or two and do a little research on he subject---there are books on the topic

Additionally, just clear the codes and do not buy anything until the fault returns.