Last week we serviced a 58 plate BMW 325i with the 3Ltr N53 engine. Customer came back today with engine management light on (and in limp home mode) and after taking a look we have the following fault code stored.

29F2 - Fuel high pressure system, fuel pressure - Lower rail pressure threshold value undershoot.

When erased, comes back within a few seconds.

Quick search of the internet reveals massive issues with the High Pressure fuel pumps mainly on the 335i N54 engines but also on other engines including this N53 version. It seems we're unlucky that this fault should occur so soon after us servicing it.

Found the following BMW tech bulletin (see link below).

https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CC8QFjAA&url=http%3A%2F%2Fwww.1addicts.com%2Fforums%2Fattachment.php%3Fattachmentid%3D422835%26d%3D1282710456&ei=5NDvUqbkGYmR7AalmYGYBw&usg=AFQjCNFtOOcPNZ341DMmtviSQsIjC343OQ&sig2=ocGUlx8PrzsMrDDUrpttzQ&bvm=bv.60444564,d.ZGU

We have a low fuel rail pressure of approximately 5600hPa (5.6 bar)which we think is in spec so the low pressure sensor is ok, so the tech bulletin seems to suggest that as our pump's part number ends in 30x that the vehicle will need the correct software download and a new pump installing.

Just looking for some support as to whether anyone else has changed a pump for this problem and how tricky is it?

We will need to get the software level checked on the car so I'm hoping someone I know with an Autologic will be able to help out there....

Thank you for your time.

Cheers

Sean