GezaBMX

Hi everybody,

I drive a 2003 CLK 240, recently I took my car to a mechanic who told me that I have to change the O2 Sensor on drivers side(left) behind the cat. He also told me that I should get OEM not aftermarket. My problem is that I don't have a part number and I don't want to buy the wrong sensor.

Regarding the kill switch, I would like to fit a hidden kill switch since car theft is a slight issue where I live. Anyway, I was thinking that I would check out which fuse goes to the ignition barrel and I would put a switch on the circuit since I know if I disconnect the battery then the car will lose it's memory, this is why I was thinking about the ignition circuit. If anybody has a better idea or any advise I'm always open for more experienced peoples opinion.

Best regards,
Geza

Sorry if there is another thread about this but I wasn't able to find it.

labguy

I recently purchased an O2 sensor at autozone. I didn't need the part number just year make and model and upstream or downstream. The oem part was $399 and the aftermarket Bosch part was $159. I bought the Bosch part.

GezaBMX

Hi labguy,

The OEM part is about the same price as my mechanic quoted me.
I'm thinking if I should get maybe a used OEM part or should I purchase the aftermarket Bosch?

labguy

Well, you know what I did. I bought the Bosch part.

Maybe someone with more knowledge than I can chime in on this....

johny1989

bosch or oem is the exact same the only differnce is the socket which is a 2 min job to fit.
get the bosch or a used oem. they fail every 250 000 or so so no worries.
the most common issue when a o2 sensor fails is the stumble on acceleration. like a misfire lag for a sec or so. along with the cel light.

the part number for the original is 0015407417 , all four o2 sensors seem to be the same .

good luck

GezaBMX

Thank you Johny. That's the same thing I'm feeling, a lag or sometimes a stumble when I step on it. But it's not that big of an issues so I will leave it for January.
Regarding the kill switch, do you have any idea? Do think I'll get any errors if I put a disconnect switch on the ignition system somewhere?

gaazmon

Regarding this second part, it's usually safer to use a kill switch to interrupt the starter instead of the ignition. The least expensive ones are the ones that you wire to a 12volt source to disable the system (light switch, window switch, etc). Some use a keypad requiring a disarm code (these are cool as they have a very nice visual deterrence for thieves). The advance ones use a wireless tag you hang from your keychain and the system detects when the tag is nearby to automatically disarm the system, so no user input required. Hope this helps!

GezaBMX

@gaazmon, thank you for your advice. In the following week I will get started on this. Will report back soon as it's fitted.

Thank you everybody for your help!!!
Happy holidays.

Rudeney

For a kill switch, I'd tap into fuse #53 on the front SAM. It's for the starter relay and with that circuit interrupted, there will be no cranking:

http://benzbits.com/w203/FrontFuses.pdf

GezaBMX

Thank you very much Rodney. I was thinking of something similar as well. Hopefully there will be no error codes or CEL.

Rudeney

Nope, none at all. I have pulled this fuse several times on the kid's C240 when she was grounded.

pskdude

I used 4 of these suckers on mine and I was error free. Just a little more work to cut and tie together. But worked great. for 160. I changed all 4. Front and back.

http://amzn.com/B000BZG8ZU

GezaBMX

Hi everybody,

So I finaly managed to install the switch. It works perfectly without giving any errors or malfunctions. At least now I sleep better at night.

Thank you for everbodys help, wish you all a Merry Christmas and Happy Holidays.