[lowrydr310]

I have two low pressure fuel system codes on my 335 that pop up periodically:

2AAF
2A2D (P3096)

I'm aware that the early version of these sensors are known to fail. Mine is original from 2007. How can I diagnose properly to determine if it's just a faulty sensor or an actual failing fuel pump?

[lowrydr310]

Bump..

It's too bad newtis got shut down. Any chance ISTA has the diagnostics procedures? Where's gbalthrop when you need him?

I'm trying to understand how the low pressure fuel system works; when the pump is commanded to turn on, what regulates pressure, and what I should be looking at as the source of these codes - failing pump or failing sensor.

I tried component activation in INPA and then checking pressure on one of the other menus and it's showing zero, despite clearly hearing the fuel pump running. When unlocking the doors I can hear the fuel pump priming significantly longer than the two other E90s I have.

[lookalikehuuh]

Any idea what the pressures are? If you can grab a log of a run maybe we can help you diagnose?

Normally your LPFP should be averaging around 72PSI. Do you have just a OE fuel pump or an upgraded fuel pump (it being a 335 and me assuming its tuned, lol)

[lowrydr310]

Originally Posted by lookalikehuuh

Any idea what the pressures are? If you can grab a log of a run maybe we can help you diagnose?

Normally your LPFP should be averaging around 72PSI. Do you have just a OE fuel pump or an upgraded fuel pump (it being a 335 and me assuming its tuned, lol)

Completely stock 335i, I'm sorting out some basic maintenance before I do anything, which includes this fuel pump diagnosis. No MHD yet so I have no logging capability. It's an original fuel pump which I don't plan to upgrade as i do not plan on any aggressive tuning.

I tried checking pressure in INPA with the engine off after activating the pump manually and it shows zero but that doesn't make sense. Need to try that menu again with the car running.

[lowrydr310]

I tried checking pressure in INPA with the engine running and all looks good. I don't recall the specific value since I'm unfamiliar with the units but it was in the green bar near the upper end of the range fluctuating slightly. I'm still unsure how to properly diagnose this. I'd like avoid throwing parts at it unnecessarily. I get the two codes mentioned in my first post above, and I get an occasional stumble/hesitation off idle. Off idle throttle response is very jerky too, like I'll press the accelerator and there's a delay then it accelerates abruptly.. too abruptly.

I'm taking care of a bunch of preventative maintenance that might address this: boost solenoids, new vacuum lines, new plugs, and new coils. I cleaned the vanos solenoids but didn't replace. The fact that I have fuel codes leads me to believe there's a fueling issue and I don't know how to distinguish between a sensor problem or a pump problem.

The pump seems to prime significantly longer than my other two E90s. The other cars it primes for about a second or less. This thing primes for several seconds, however there are never any issues starting this car even if it's been sitting a week. Crank time is very short and it fires up immediately.

[gbalthrop]

Originally Posted by lowrydr310

I have two low pressure fuel system codes on my 335 that pop up periodically:
2AAF
2A2D (P3096)
...How can I diagnose properly to determine if it's just a faulty sensor or an actual failing fuel pump?

Originally Posted by lowrydr310

Bump... It's too bad newtis got shut down. Any chance ISTA has the diagnostics procedures? Where's gbalthrop when you need him? [Sorry, I don't have N54, so figured I'd let someone else help. See Below.]
I'm trying to understand how the low pressure fuel system works; when the pump is commanded to turn on, what regulates pressure, and what I should be looking at as the source of these codes - failing pump or failing sensor. [Pressure Regulator on Left Side of Tank (per diagram attached to NEXT post). See BMW Fault Code Lookup Fault Definitions and Fault Info Links below for HOW to diagnose: Pump vs. Sensor.] ...

Originally Posted by lowrydr310

I tried checking pressure in INPA with the engine running and all looks good. I don't recall the specific value since I'm unfamiliar with the units... I don't know how to distinguish between a sensor problem or a pump problem. [See Below]...

Since there were major electrical changes (JB Fuse Panel, Contents of E-box, etc.) effective 3/1/2007, in MIDDLE of 2007 model run, ANYONE with 2007 model should always post build Mo/Yr, or Last-7 Characters of VIN, to allow CORRECT wiring diagram info from ISTA. Since TIS "closed" 10/2020, ISTA is best source of all Documents, such as "SSP" wiring diagrams, "REP" Repair Procedures, "FUB" Functional Descriptions of HOW systems work, etc.

You can download ISTA from the MEGA Link in attached pdf: 1 E9x References. You can use ISTA as a Shop Manual, WITHOUT being attached to vehicle, which means anyone with Windows 10/11 OS computer (Opt-OUT of S-Mode), can install ISTA and see all of the "Goodies". Just enter Last-7 Characters of VIN in "Input VIN" box which appears when you click "Operations" Menu Button, and follow the instructions in attached pdf: ISTA as Shop Manual.

Here are BMW Fault Code Lookup Definitions of your two codes, and Links to Fault Info Sheet for EACH. The "Service Notes" suggest tests (using pressure gauge attached to "Fuel Rail"), to determine whether Sensor or Pump/Regulator issue:
2AAF | DME: Fuel pump, plausibility | msd80 | Engine electronics
https://bmwfault.codes/XMLDiagView?d...IAMQA3ADAANAA=

2A2D | DME: Fuel low-pressure system, fuel pressure | msd80 | Engine electronics
https://bmwfault.codes/XMLDiagView?d...IAMQAxADAANAA=

As far as Pressure Units, and correct LPFP pressure:
72.5 PSI = 6 bar = 600 kPa (kiloPascal).
My 328xi with N52K engine has NO pressure sensor, and NO HPFP, so I cannot say WHAT Live Data INPA or ISTA should show. INPA shows CONSTANT 600 kPa when Pump is running, but there is NO actual pressure sensor (AFAIK).

HOWEVER, your N54 has TWO Pressure Sensors, Low Pressure supply from LPFP, and Rail Pressure as supplied by HPFP. Presumably either INPA or ISTA can show those values as Live Data, DME (MSD80) > F5 Status in INPA, and DME Diagnosis Scan in ISTA.
George

[gbalthrop]

Attached is Bentley Fuel System Schematic for N54, related to Prior Post.
George

[lowrydr310]

I got an alert on this thread that it's 'popular' in searches and forgot I had posted this. The issues were resolved. 2AAF is the shadow code for "fuel pump plausability" and still comes up intermittently. I replaced the stock EKPM2 with a EKPM3 and coded it, the 2AAF doesn't appear as often, but still shows up once or twice a year.

The 2A2D code was caused by a faulty low pressure side fuel pressure system. I did some data logging and saw my low pressure was reading around 50PSI but would occasionally dip down to single digits or even 0. I also had some jerkiness at low throttle. I replaced the low pressure sensor with the revised part (and required adapter) and it has been running great since then.