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· Registered
Clk 350
27 Posts
Discussion Starter · #1 ·
Hi guys

I hope you all had a good holiday season.

I have a code coming up relating to an ageing o2 sensor downstream of my left catalytic converter.
Po515 left o2 sensor (after twc) ageing po159

I have then had another code pop up a few days later saying the left cat efficiency is insufficient.

Is it likely that a failing o2 sensor is the cause of the ecu thinking the cat isn’t working properly?

Is the sensor replacement an urgent job? Can I wait until the weather is a little better :)
Can the failed sensor do any damage?

Many thanks

· Banned
2005 Mercedes CLK320 2008 Mercedes E550 2014 Mercedes E63 AMG
1,183 Posts
With the downstream sensor failing, I would recommend changing all four. Use a name-brand sensor and not something for $15. That is my suggestion.

You cannot trust the codes until the sensor is reliable. Hope this helps.
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