I have an 1991 300SEL. When I drive, the check engine light comes on for about 15 seconds and then disappears. My hunch is that the O2 sensor needs to be replaced. Please help. Is my hunch correct? What does the sensor look like and what is the correct procedure to replace it? Any help would be appreciated b/c I want to save a few bucks. Thanks a bunch. By the way, if I replace the sensor,do I have to get the light reset since it goes off by itself now?

Raghu

First, nice car. The 300 SEL is a solid machine. Not much power, but enough to get around. Surprise me that MB does not put the 3.0 L engines in the S-Class anymore.

I'm no guru, but I think that your hunch is correct. Same thing happened to my 87 Camaro a while back. Once the sensor was replaced, no more light. My O2 sensor was on the exhaust pipe downstream of the exhaust manafold.

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'89 420 SEL
'90 300 SEL
'68 Olds 88 Convertible
'84 300 SD (sold it)