O2 Sensor Failure? symptoms? - The Unofficial BMW M5 Messageboard (m5board.com)

Stamper1 · 5th June 2008, 19:22

I need some help here guys, need to know what the symptoms are for o2 sensor failure?. Would it induce limp mode?, and what would cause it to fail?. How much labor is involved to replace them and what are the costs involved?. Whats the primary function of the o2 sensors?. Thanks in advance.

Neil.D · 5th June 2008, 19:39

Hi Stamer,

the O2 sensors read the fuel/oygen levels from the exhaust and adjust the mixture accordingly.
Symptoms can be poor fuel consumption, black soot from the exhaust, poor accelleration, hesitancy - to name just a few.

Im not sure but it could induce limp mode if one is on its way out.
The engine may do so in order to protect itself as mixture is important.

Mine were replaced recently, the parts were £130 each (there are 2) and about 20 mins fitting. In total all was about £330. Sorry dont know conversion rate.
If you have a ramp/pit all you need is a screw driver and a spanner really. I think there are instructions in the FAQ area...

Neil

everycredit · 5th June 2008, 19:48

Failure in O2 sensor would throw a SES light, whose code correspondes to an O2 sensor failure. Each sensor is about $100 off of pelicanparts.

Mike S. · 5th June 2008, 21:10

This post might help you out a little bit if you decide to replace them:

http://www.m5board.com/vbulletin/sho...6&postcount=25

The info is almost a year old, so the prices might have gone up.

This is an easy DIY. Extremely easy.

jclyman · 5th June 2008, 21:49

Quote:

Originally Posted by Neil.D

...
Mine were replaced recently, the parts were £130 each (there are 2) and about 20 mins fitting. In total all was about £330. ...
Neil

I believe there are 4 (2 pre-cat, and 2 post-cat). The pre-cats are the ones you speak of in your post, Neil.

The post-cat sensors compare their readings with the pre-cat ones. Too much difference, MAY trigger an SES light.

At least, that's the way I understand it.

everycredit · 5th June 2008, 22:31

Quote:

Originally Posted by Mike S.

This post might help you out a little bit if you decide to replace them:

http://www.m5board.com/vbulletin/sho...6&postcount=25

The info is almost a year old, so the prices might have gone up.

This is an easy DIY. Extremely easy.

ja, just make sure the car is cold first.

Neil.D · 5th June 2008, 23:20

Quote:

Originally Posted by jclyman

I believe there are 4 (2 pre-cat, and 2 post-cat). The pre-cats are the ones you speak of in your post, Neil.

The post-cat sensors compare their readings with the pre-cat ones. Too much difference, MAY trigger an SES light.

At least, that's the way I understand it.

Such attention to detail...

indeeed there are. 2 pre and 2 post. The Post just measure the emissions post cat to ensire the CATS are working correctly.

I hear that should your CATS, and therefore your emmisons be ruined then the SES light flashes at you...

Neil

Stamper1 · 6th June 2008, 11:28

THANX FOR THE HELP GENTS

RUFM5 · 6th June 2008, 14:21

I bought the pre CAT O2 Bosch#13477 sensors for $57 each at Rockauto. Not a bad deal.

http://www.rockauto.com

hailey198 · 3rd August 2008, 19:24

Bimmer Specialist

I found this company that sells before cat sensors OEM for $60. This is the best price I could find. Post cats at $95.

When I replaced mine, the car had significant improvement in performance. The car had been misfiring a bit and definitely hesitating.
It runs great now. Cleared sensor codes and SES light is gone. Hopefully for a while. I have a 2000 M5 with only 36,000 miles. The car sat idle for some time and I think no matter what these sensors go bad with time. MAF sensors were replaced just prior! - Hailey