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hancock1701 · 05-10-2015, 04:13 PM

Hey guys,

The BMW Service Manual for a 2009 3 series says that their O2 sensors have a warranty of 100,000 miles. They also recommend changing the O2 sensors at 120,000 miles because, according to the manual, O2 sensors wear based on miles driven.

I don't like to replace good, working parts. However, I want to keep my car in good working conditions, and always try to do all the preventative maintenance so that there won't be long term damage to the system. As I understand, the pre cat O2 sensors are responsible for monitoring the air fuel mixture, and can cause not so ideal conditions downstream when they are not at their 100%. My car is currently at 140,000 miles, which to me is a reasonable service life for an O2 sensor. What do you guys think?

05-10-2015, 04:13 PM	#1
hancock1701 Registered User Join Date: May 2013 Location: Orange County, California Posts: 266	O2 Sensor Replacement, When? Hey guys, The BMW Service Manual for a 2009 3 series says that their O2 sensors have a warranty of 100,000 miles. They also recommend changing the O2 sensors at 120,000 miles because, according to the manual, O2 sensors wear based on miles driven. I don't like to replace good, working parts. However, I want to keep my car in good working conditions, and always try to do all the preventative maintenance so that there won't be long term damage to the system. As I understand, the pre cat O2 sensors are responsible for monitoring the air fuel mixture, and can cause not so ideal conditions downstream when they are not at their 100%. My car is currently at 140,000 miles, which to me is a reasonable service life for an O2 sensor. What do you guys think?