The E90 diesel 316d is experiencing a condition known as limp mode, which is accompanied by a noticeable decrease in fuel pressure.

[BuffUpdate]

My 2010 E90 LCI is malfunctioning.
The engine requires around 4 seconds of cranking to start.
Once initiated, the vehicle will maintain a speed of 80 miles per hour on the road. However, it may experience stalling and engine shutdowns in urban areas, particularly while accelerating.
It will thereafter reboot after a brief period of time.
The limp mode indicator illuminates when I have difficulties.

I have a suspicion that the fuel pressure is low and I am now seeking advise on whether I should replace the lift pump in the tank, the fuel pressure regulator, or the fuel pressure control module.

The Foxwell code reader I purchased is ineffective. The report indicates that no errors or issues were detected.
I replaced the fuel filter and inspected the injector leak off, finding no issues. The diesel particulate filter (DPF) is clean and successfully undergoes regeneration. The glow plugs are quite new. The vehicle has accumulated a mileage of 135,000 kilometres and was manufactured in the year 2010.
Do you have any opinions or ideas to share?

[MundeDas]

In order to detect any faults, it is necessary to scan the device using a functional tool. This is important since the warning light or the half engine power light may have been activated.
Which specific model of Foxwell diagnostic tool have you bought, since Foxwell products are generally of good quality?

[BuffUpdate]

Thank you,MundeDas,,for mentioning the Foxwell NT650.
Although I may lack intelligence, I performed a vehicle scan at my residence when the limp mode indicator was not on. Perhaps I should consider pulling over to the side of the road and use the limp mode indicator to do a scan.
I am capable of reaching a speed of 80 miles per hour while I am in 6th gear, allowing the gasoline to flow properly. However, if I attempt to accelerate in lower ratios, the issue arises immediately.
I expected a defect to be recorded and stored.
The integrity of the in-tank lift pump may be questionable, since it experienced freezing over the winter a few years ago, necessitating a wait until the gasoline thawed due to the presence of water in the fuel or waxing.
I have not replaced the pressure regulator or module, and I am concerned that the high-pressure fuel pump (HPFP) may be contaminated with swarf. I have not observed.
Instead of just replacing several costly components, I want a methodical and rational approach.

[MundeDas]

The foxwell scan identifies the modules that are responsible for logging faults.
It would be advisable to upload it to ista in order to increase the likelihood of identifying the error.

[BuffUpdate]

I attempted to get ISTA.
I dedicated two days to the task of retroactively installing Windows 7 and related software onto my Windows 11 computers. Did not make any progress.
I am unaware of the specific modules that the Foxwell examines, but, it does indicate that there are no defects detected.

Which component is the most likely to be malfunctioning?

I am capable of replacing the fuel pressure sensor.
Next, the gasoline tank lift pump.
Next, the module responsible for controlling fuel pressure.

The price for the first scanner is £45, then it increases to £120, and finally to £59. In comparison, another scanner costs £400.
I have a strong affection for this automobile and am eager to repair it.

[MundeDas]

What is your location? It's possible that someone nearby has expertise in the area you need help with and may be willing to assist you in exchange for a small reward.
If you are in close proximity to me, you are cordially invited to bring your ista for a proper diagnostic and repair, rather than attempting to fix it by randomly replacing components.

[Talentrews]

Does the Foxwell automatically detect your car?

[BuffUpdate]

I am now located in Yorkshire, namely between the cities of Leeds and Goole.
The Foxwell NT650 seems to have a rudimentary design, and I had to install the software onto it in order to use it with my automobile.
It functions primarily as a service light reset tool rather than a comprehensive scanning.
Amazon.co.uk

[MundeDas]

I own the premium edition of that product, which is a multifunctional scanner. However, its scanning capabilities are restricted to certain platforms.
I feel there may be a malfunction in the Electronic Key Programming (EKP) system that cannot be detected by the Foxwell scanning tool.

[BuffUpdate]

Indeed, I seen a YouTube video on this matter, where the individual disconnected his Electronic Control Unit (ECU), resulting in the continuous operation of the fuel pump located inside the fuel tank. If that statement is accurate, it will assist me in identifying and resolving any issues.
Nowadays, things are becoming further intricate and challenging to ascertain.
Today, I will begin with the execution of the EKP.
I really appreciate your assistance.

[MundeDas]

I fail to comprehend the causal relationship between disconnecting the Electronic Control Unit (EKP) and the perpetual operation of the pump. If the output (small plug) is removed, the pump becomes completely unplugged. If the large plug for the input is unplugged, then no power can be supplied to the low pressure pump.

[BuffUpdate]

I have just purchased a pre-owned EKP module from the online marketplace eBay. At a price of £20, it is highly recommended to give it a try.
I will attempt to locate the YouTube video, however there are several videos available, indicating that the EKP (Electronic Keying Protocol) may be experiencing issues.
Conceptually, I am obligated to programme the substitute component for my automobile. I am unable to do so, thus we will observe and ascertain the outcome.
I will inform you of my progress.