2000 BMW 323 BMW with service engine soon light

E46BIMMER

MEMBER
2000 BMW 323
6 CYL
2WD
AUTOMATIC
185,300 MILES

I have a 2000 BMW 323i with the service engine soon light on. It has been on for about two weeks now. I scanned it and retreived the following codes: P1188, P1189, P1478, P0170, P0173. I replaced the thermostat yesterday because it was stuck open causing the engine to never warm up properly, then I cleared the codes. I thought this would correct the codes as they refer to the short term fuel trim, but it came back on today and when I scanned it I got P1188, P1189 which I looked up and they refer to the O2 sensors B1S1 and B2S2. I thought it was a pretty long shot that they are both bad at the same time. Any advice would be great. Thanks!

5 Replies

DOCHAGERTY

MECHANIC
9,601 POSTS

At 185k, why not replace them?

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Saturday, December 12th, 2009 AT 9:51 AM

E46BIMMER

MEMBER
3 POSTS

I find it hard to believe that both front sensors on bank 1 and 2 have gone out at the same time. Seems like it should be something common to both banks. I just hate to guess at the problem and not be sure that will fix it.

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Saturday, December 12th, 2009 AT 2:51 PM

DOCHAGERTY

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9,601 POSTS

Replacement is called for at 100k, you are at 185k. Is that correct?

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Saturday, December 12th, 2009 AT 9:34 PM

E46BIMMER

MEMBER
3 POSTS

Yes that is correct, but I just find it hard to believe that both of them went out at the same time. I was not aware that they replace them as preventive maintenance, why is that? I will try and scan it again tomorrow and look at the freeze frame data to see what that says.

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Thursday, December 17th, 2009 AT 10:57 PM

DOCHAGERTY

MECHANIC
9,601 POSTS

As Oxygen sensors age they often have a tendency to become biased towards the lean side. Freeze frame data indicates what voltage the sensor is producing, not it's calibration. You usually cannot perceive a lean condition sensor, but it will show up in reduced emissions, especially NOX. I hope this helps you out, it is always good to be able to make an informed decision.