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Old 08-14-2002, 12:42 AM
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02 Sensor replace even if no check engine light?

I am new to this forum after doing a TON of reading on the wiring harness problems on the 93-95 mercedes here...thanks for all the great info. I have a 95 c220 which has finally succumbed to this symptom at 97K mi when the check engine light came on.

I first took it to the dealer where they said to replace the engine and coil harness and the 02 sensor. I thought it was odd they could diagonse the 02 sensor when the wiring harness was crumbling. Anyway, their price was absurd and didn't do much wih the goodwill warranty so I took it to an independent Merc mechanic and they verified the harness needed replacement and also extrated other sensor codes which they said probably is a result of the bad harness.

The car is still in the shop but they replaced the harnesses and all seems well so far. They have been driving it and the check engine light doesn't come on.

My question is: Should I replace the O2 sensor even though the check engine light doesn't come on anymore? From what I have read here, the 02 sensors tend to need replacing around 100k miles anyway. Or should I just hold off until the light come on and the codes says to do it then? What harm am I doing by not changing it now?

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Old 08-14-2002, 01:15 AM
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Join Date: Jun 2000
Location: Dubai, United Arab Emirates
Posts: 238
For what it is worth, the check engine light came on recently on my 500E. I tried resetting it myself and after a few days it came on again. I took it to the shop and the dealer reset the light and told me there was nothing wrong, I paid him a few dollars and left after half an hour. That was about 2 months ago and it it still running fine with the light out !
1993 190E 2.0L (Euro.) sold
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Old 08-14-2002, 02:27 AM
public enemy
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If I were you I would not change it yet, since there seems to be no problem with it.
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Old 08-14-2002, 08:01 AM
Join Date: Mar 1999
Location: Tucker, Ga USA
Posts: 12,153
NO, don't replace a part that is still working! The check engine lamp will come on & you will get a code for the O2 sensor when it is bad OR even tired(slow response).
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Old 08-14-2002, 10:06 AM
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Great thanks for the advice. Gives me time to rebuild my piggy bank after this $$$ service!

They had to replace the engine, coil, and air pump wiring harnesses and replaced a cracked vacuum block. I should be getting my car back today and hope it's gonna run smoother now!

Is there anything I should have asked the Mech to check as well?

I have read alot about the OVP here but don't understand what the symptoms would be to require replacement.
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