P1209 code that I cannot solve

[vtm3]

A local mechanic very experienced and trustworthy is doing all the work for me. But I am having no success getting p1209 fixed on my 08 m3.
When accelerating normally it will occasionally go into limp mode.
Replaced booster vacuum hose. Still the same.
Replaced fuel pressure sensor and vacuum pump. Same.
Any thoughts on next steps would be appreciated.

[Green-Eggs]

Originally Posted by vtm3

A local mechanic very experienced and trustworthy is doing all the work for me. But I am having no success getting p1209 fixed on my 08 m3.
When accelerating normally it will occasionally go into limp mode.
Replaced booster vacuum hose. Still the same.
Replaced fuel pressure sensor and vacuum pump. Same.
Any thoughts on next steps would be appreciated.

I hope this helps.

https://www.m3post.com/forums/showpo...7&postcount=17

[omgzirra_exe]

what other warning lights are you getting? i know a few friends had dropped a bit of brake fluid on the sensor and it cause them to go into limp mode often

[vtm3]

Thank you for the response. Any help is much appreciated. Green-eggs I will forward that to my mechanic and continue to research. It’s pretty frustrating because it can drive fine fast and aggressive and then just …… limp

[Adriano917]

I had the exact same issue, but mine ended up being the brake booster vacuum pump. If you already replaced that and the hose, more than likely its the vacuum sensor under the brake booster or a leak on vacuum hoses

[Adriano917]

Was the brake vacuum pump replaced with a new one ?

[vtm3]

All news parts, vacuum hose with sensor(34302283605), fuel pressures sensor (13537622231) vacuum pump (343332283333). And is there another sensor, other than the one attached to the booster hose?

[Adriano917]

My issue was the same and I could not figure it out for the life of me, I also replaced the hose and the sensor under the brake booster part # 34302283605. I checked all the lines for leaks with some brake cleaner to see for any high idle and nothing, I suspected the brake booster pump but it was working since you can hear it. I got tired and took it to a friend of mine who owns a shop and specializes in BMW’s, he double checked everything and turns out the brake booster pump was not pulling enough vacuum. Pump was replaced and voila no issues since then. Its odd that you replaced all that and still having the same code, I’m thinking a leak.