CEL comes on, then back off - Benzworld.org

MRBSMITH · 02-02-2008, 02:04 PM

Hello Forum;
I need the wisdom of the forum.

I had a CEL (Check Engine Light ) that would come one, and then before I could check the code, go back off. Then when I checked the codes I got no malfunctions.

Finally, I caught the codes with the light still on;

2 codes, P0134 - O2 Sensor Bank 1 Sensor 1 - no signal
and - O2 Sensor Bank 2 Sensor 1 - no signal

So my question is, should I jump in and replace sensors or what.........

Ideas?
B

ohlord · 02-02-2008, 03:06 PM

pre cat sensors,autohausaz.com oem.
check all wires to them.You don't say how long this has been going on ignored so since it was in open loop operation you may want to check the cats to see if they are damaged.
How many miles?under 80k the dealer will check them for you on the 8/80 rule
ohlord

gregs210 · 02-02-2008, 03:48 PM

With them just coming on and going off I'd lean towards ohlord's suggestion and start checking the connections, starting with the ends themselves, pull them off and look for corrosion, broken wires, etc. If that looks good then check the wire path to ensure the integrity of the wires leading to the sensors.

If everything looks okay then the sensors probably are heading south.

Take care and enjoy the ride,
Greg

MRBSMITH · 02-03-2008, 06:56 PM

Is that a California only rule?

B

mbforcyndi · 02-03-2008, 07:09 PM

8/80k emission control is not just California.

My '02 is at the dealership currently having the cat converter replaced under emissions warranty in Md. (Though the car is being registered in NY).

cyndi

MRBSMITH · 02-10-2008, 06:44 PM

The Cel light came on again, and the same codes, MB out of O2s so I drove it.

I had to get to a golf match 60 out in the desert and I was late..... so.... I cut the car loose on LA freeways, 110+ mph and.

The light went back off, all wiring/connects are OK. But now the car runs really great.

I keep this car in 'granny mode' all of the time to save fuel, could this be causing a build up on the O2's that needs to be blown out now and then?

I will replace all 4 o2's soon as a precaution.

B

**Musikmann** · 02-10-2008, 07:53 PM

Quote:

Originally Posted by MRBSMITH

...I keep this car in 'granny mode' all of the time to save fuel, could this be causing a build up on the O2's that needs to be blown out now and then? B

That's the way I was driving too and was burning oil. Once I started driving harder, oil consumption improved. I don't know what effect 'granny mode' has on the O2 sensors but I think that is a possibility. I think most MBs are happier if they are driven hard, but that is just my humble opinion. Good Luck!