I have a low pressure fuel regulation fault (VCDS scan below). I replaced the fuel filter and low pressure sensor, but still have the fault. I naturally suspect the low pressure pump next, but before I replaced it I wanted to verify that the pressure was actually low. However - while I found the measurement blocks for specified and actual fuel rail pressure, I couldn't find the specified low pressure. I though I found the actual low pressure, but it's so low as to be unbelievable.
I logged "Current - Fuel Pressure" (103-0), spec/actual fuel rail pressure (106-2, 106-0) and "Electric - Fuel Pump 1/2 Load" (106-1) while driving around a bit and pushing the car to redline. Spec and actual rail pressure tracked very closely, ranging from 23bar at idle to 136bar at WOT, and pump duty cycle (I think that's what it is...) stayed between 50% and 60%, except under WOT when it peaked at 82.4%. The weird thing is that the low pressure stayed stuck at 0.23 bar.
Is it possible that the high pressure pump could have performed as well as it did with that little inlet pressure? Or am I measuring the wrong thing? I couldn't find another measurement in the Advanced Measurement blocks that looked like low side fuel pressure.
VCDS Scan:
Address 01: Engine Labels: 07K-907-404-CEP.clb
Control Module Part Number: 8J0 907 404 R HW: 8J0 907 404 M
Component and/or Version: 2.5l R5/4V TFSI 02 0070
Software Coding: 0113000A180F0160
Work Shop Code: WSC 01236 785 00200
VCID: 3C21359BBA6173CA92B-8069
1 Fault Found:
012555 - Low Pressure Fuel regulation
P310B - 002 - Fuel Pressure Outside Specification - MIL ON
Freeze Frame:
Fault Status: 11100010
Fault Priority: 2
Fault Frequency: 2
Reset counter: 255
Mileage: 96650 km
Time Indication: 0
Date: 2025.09.21
Time: 16:42:25
Freeze Frame:
RPM: 1192 /min
Load: 20.4 %
Speed: 0.0 km/h
Temperature: 93.0°C
Temperature: 60.0°C
Absolute Pres.: 800.0 mbar
Voltage: 14.224 V
I logged "Current - Fuel Pressure" (103-0), spec/actual fuel rail pressure (106-2, 106-0) and "Electric - Fuel Pump 1/2 Load" (106-1) while driving around a bit and pushing the car to redline. Spec and actual rail pressure tracked very closely, ranging from 23bar at idle to 136bar at WOT, and pump duty cycle (I think that's what it is...) stayed between 50% and 60%, except under WOT when it peaked at 82.4%. The weird thing is that the low pressure stayed stuck at 0.23 bar.
Is it possible that the high pressure pump could have performed as well as it did with that little inlet pressure? Or am I measuring the wrong thing? I couldn't find another measurement in the Advanced Measurement blocks that looked like low side fuel pressure.
VCDS Scan:
Address 01: Engine Labels: 07K-907-404-CEP.clb
Control Module Part Number: 8J0 907 404 R HW: 8J0 907 404 M
Component and/or Version: 2.5l R5/4V TFSI 02 0070
Software Coding: 0113000A180F0160
Work Shop Code: WSC 01236 785 00200
VCID: 3C21359BBA6173CA92B-8069
1 Fault Found:
012555 - Low Pressure Fuel regulation
P310B - 002 - Fuel Pressure Outside Specification - MIL ON
Freeze Frame:
Fault Status: 11100010
Fault Priority: 2
Fault Frequency: 2
Reset counter: 255
Mileage: 96650 km
Time Indication: 0
Date: 2025.09.21
Time: 16:42:25
Freeze Frame:
RPM: 1192 /min
Load: 20.4 %
Speed: 0.0 km/h
Temperature: 93.0°C
Temperature: 60.0°C
Absolute Pres.: 800.0 mbar
Voltage: 14.224 V
