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Old 11-30-2013, 01:35 AM
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Catalytic Converter Error Code 29F4, 29F5, CEL

Last winter I got the CEL on the coldest day of the year (2 or 3 times). It only happens when I park the car for up to 8 hours and temp is below 19F (-7C).

What I noticed was after 2-3 engine restarts the light goes off, or if I leave the car overnight CEL is gone the next day (covered garage). No CEL in the summer or any symptoms, car drives excellent.

Yesterday we got a cold snap and car is left at the train station for 9 hours, get back and CEL pops up, so I got my INPA and read the codes, 29F4 and 29F5.

What could be causing this on cold days alone? its a 2007 3.0....
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Old 11-30-2013, 02:36 PM
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These are catalytic conversion efficiency codes, I believe

These happen when the post cat O2 sensor "sees" too much variation in the O2 waveform. (the pre-cat sensor should see a value that oscilates around stochipmetric, whereas the post cat should see a much attenuated signal- when it doesnt it assumes the cat is bad)

MANY, MANY things OTHER THAT BAD CATS can cause this issue.

But first, be aware that BMW has a federal warranty for the cats- if the cats are bad and you are under 8/80, bmw will cover it.

Common causes are running too rich, overwhelming the cats, the post cat o2 sees too much fuel.

Air leaks, engine running cold, bad thermostat, MAF issues...etc..etc

You need to have more than codes. Any chance you can look at fuel trims?

A
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Old 12-01-2013, 04:20 AM
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Thanks Ard, I am at 96k miles

I don't get any fuel trim codes ...unless I am not reading it well

Considering this happens only on the coldest days of the year, CEL comes on within 30 seconds of starting the car after leaving it in the cold for more than 8 hours and CEL goes off by itself in a couple hours or couple restarts, does it even point to any thing or things?

I know it's tricky just guessing..
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Old 12-01-2013, 01:13 PM
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NOT CODES!

'read fuel trims'

The biggest problem I see in on-line forums (and many smaller, lower quality shops) is a reliance on "codes" to diagnose and fix cars.

Obviously, this is the first thing to check, and most people can get a code reader for a reasonable price.... And indeed 'we' have gotten pretty good at correlating "code+symptom to probable failure"... but some issues just cannot be fully diagnosed that way.

All cars with an ECU have 'fuel trims'- this is the amount of fuel the ECU (DME) is adding to 'correct' the AFR between the value derived from the airflow sensor and the value derived from the Pre-CAT O2 sensor. The DME allows a significant amount of correction before a code is tripped- so fuel trims can be whacked, no code yet- but too much fuel and you get a cat code. Or the vanos is running sluggist- still 'sub code'- but enough run rich.

I suppose also it could be an o2 sensor- precat perhaps? Have you changed this ever?

Last edited by ard; 12-10-2013 at 02:02 AM.
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Old 10-19-2018, 11:40 PM
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Hi there, did this ever get resolved?
I'm having the same problem, just two codes nothing else. 29F5, 20F4. The car runs fine. I already cleared three times, this last time I let it stay and continue driving and checking for additional codes. NOTHING just the two codes I mentioned.
I have an X5 3.0si 2008 with 133,000 miles on it.
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Old 02-23-2019, 01:23 AM
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Any fix to this 08 4.8 x5 . Same codes fixed valve stem seals no more smoke out the tail pipes I am running rich but will be changing my air filter since it's really dirty ATM
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Old 02-23-2019, 12:57 PM
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Quote:
Originally Posted by Hack213 View Post
Any fix to this 08 4.8 x5 . Same codes fixed valve stem seals no more smoke out the tail pipes I am running rich but will be changing my air filter since it's really dirty ATM
Fix your fuel and air issues. Not gonna be a dirty air filter.....
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Old 02-23-2019, 01:10 PM
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Quote:
Originally Posted by ard View Post
Fix your fuel and air issues. Not gonna be a dirty air filter.....


To be honest the air filter has not been changed in about 2 years anyways any suggestions to fix fuel and air their is no leaks no pvc hoses etc
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Old 02-23-2019, 04:09 PM
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Quote:
Originally Posted by Hack213 View Post
To be honest the air filter has not been changed in about 2 years anyways any suggestions to fix fuel and air their is no leaks no pvc hoses etc

Welp, if there are 'no leaks no pvc hoses etc', then I guess that's that- im out of suggestions.
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Old 02-28-2019, 05:16 PM
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Quote:
Originally Posted by ard View Post
Welp, if there are 'no leaks no pvc hoses etc', then I guess that's that- im out of suggestions.



Changed the filters to Mann definetly running rich can smell gas during the cold start..
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