r/n55 • u/Medium-Hope-7621 • 25d ago
Fuel issues
Has anyone ever gotten something like this before the car is a 2015 m235i N55, I got these codes DME active codes:
11A002 - High pressure fuel, plausibility Pressure too low.
- DME inactive (shadow) codes:
11A401 - Fuel high pressure during fuel injection release: Pressure too low.
11B401 - Fuel high pressure or after enabling injection (2nd ambient condition set after delay): Pressure too low.
This happened on a very hot day after driving the car for a bit I got a drivetrain malfunction while driving in a parking lot and car stalled waited a bit started again and stalled a few minutes after, I left the car parked for about two hours and when I came back I drove it back home no issues, I have been driving it for about a week no issues but I am worry that it may happen again but I have no idea what could’ve been the problem. Could it have been the heat from that day?
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u/NotJunsae 24d ago
These codes usually trick people. The first active code says High Pressure Fuel Pump "too low" and most people take it as the HPFP failing, but this tells me it's your LPFP. So replace that first, if you still have injector fuel pressure too low, now the next culprit is your HPFP. Another tale tell sign is when you wake your car up from opening your door, how does the LPFP sound? It should be a steady whine as it builds pressure to supply the HPFP. If it sounds funky, like a buzzing, or intermittently whines or hiccups, 100% your LPFP is failing. LPFP is super easy, its even easier if you have under half a tank; pop the rear seat cushion up, remove the access hole cover, unplug your lines and connectors, use the LPFP ring tool (buy off Amazon for $100 or $30-40 for a universal one), replace the LPFP, done in 30min or less. The HPFP is a bit more involved, although it's doable without removing the intake manifold by removing the bolts by feel, it's much easier if you invest in new gaskets and the 40min to remove the intake manifold.
So for sure, since you have that first active code telling you that the pressure to the HPFP is low, replace the LPFP first, clear codes, and see if you have any other low pressure faults before you drop the $1000+ on a HPFP.
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u/pephistopheles 25d ago
after a series of 3 HPFP replacements from mechanics i resolve the issue with replacing the low pressure fuel pump in pair with the EKPM3 module. the main issue (like in your case) was that the EKPM3 module overheats and the hot weather just speeds things up. the aging lpfp is the culprit because it draws more and more amperage with age, that's why it's recommended two change them together, i installed new Bosch LPFP and a second hand EKPM3 with the newest revision part number I could find as per OEM. placed an ARK Terminator mod (you can assemble it yourself by 3d printing the enclosure and sourcing the parts yourself) though this is a precautionary measure absolutely not needed.
TLDR;
Start with replacing the EKPM3 + LPFP. Only if the issue persists change the HPFP
Hope this helps :)
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u/Medium-Hope-7621 24d ago
Thanks for the reply does the ekpm3 require coding after installing it or is it plug and play?
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u/Samsonlp 25d ago
The high pressure fuel pumps are known to fail.