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      12-16-2012, 10:51 AM   #3
United Kingdom

Drives: E92 335i M Sport
Join Date: Sep 2008
Location: UK

iTrader: (0)

Originally Posted by Darkside400 View Post
Hi guys/girls, I've just bought an evolve r-cable to get my 2007 335i remaped...however I have the 29F2 error code.

"1) 29F2 fuel high pressure system, fuel pressure"

I have cleared the error, run the car for a week and its come back. It seems to occure when I have had a spirited drive home, and it occurs the next morning. Only happened twice but on startup it says "reduced power..". I re-start the car and its fine.

So, I believe I need to get the car sorted before the remap...(note, car has had the bmw firmware fix released a few years ago).

The bmw independant specialist advised me it could be the HFP sensor which would cost 100 to fix plus an Autologic code read (extra 50!).

Do I need that extra code read? they say it gives them more detail to diagnose.

Also, if its not a sensor...and turns out to be the pump, is it worth getting a warrenty to cover it? (costs alot to fix?)

Advice really welcome here.
29F2 could be map related if the tuner goes a bit overboard with the fueling and asks too much of the system. However I got no experience with Evolve's maps, but I don't think they are supposed to be that aggressive. I had a few 29F2's codes in the past when Shiv decided to push the envelope with the aggressive maps. It's quite odd that it only happens the morning after a spirited drive and it makes me wonder what software version your car is on? Do you hear the fuel pump kick in when you unlock the car? You should hear a small whine for 1-2 seconds. BMW added this to later software updates to prime the low pressure fuel system to avoid starving the HPFP when starting from cold. If you don't hear this when it's possible that your car may need to be updated. This would probably be BMW's first fix if you brought it in to them.

The code for a faulty low pressure sensor will normally be 29F3, but it's possibly that a sensor not performing 100% would cause the low pressure fuel pump not to deliver enough fuel to the HPFP. AFAIK, the sensor is fairly cheap, but it's a pain to get to. I just wouldn't expect this to only be the case when it's cold. If the sensor was going I would expect this also to happen when at WOT.

Anyway, the low pressure sensor #7 in the link below:

Replacing it is a different story. You need to remove the airbox, throttle body & intake as the sensor is hidden under the intake.
The fuzzy pictures from this post may give you an idea:

I all honesty 100+50 to replace the sensor doesn't sound all that bad if parts (sensor + intake gaskets) are included in that price. It's probably an hour's work to replace with diagnosing and replacing the part. BMW will charge that just to look at it.

Only issue with reverting to stock and dealering it, is that it may not trigger the code under these conditions. So you can either wait until it gets so bad that it fails under stock conditions or try a couple of things to fix it before going down this route.

1. Replace Low pressure sensor (~150)
2. Update software on car (if on older revision that doesn't prime the pump) ~(200)
3. Replace HPFP (~500)