D5 (D5244T to 2005) Liqui Moly Diesel Purge Gone Wrong - Now barely starting

[ca2n]

No success yet.

Took the car out today to the shops. The engine cut out three times in the span of approximately 3 minutes/300 yards. Interestingly, no cut outs in the 2-mile journey after.

All cut outs occurred at low revs/load, either on engine overrun or just barely accelerating from standstill, where the engine had well reached its operating temperature. The engine would fire again first time, every time, after cycling the ignition, which on a Geartronic means stopping and putting the gear selector into P. There were no cut-outs while the engine was warming up.

A very similar issue was detailed in this post and was remedied (thus far) by fitting a replacement fuel pressure sensor.

VIDA scan revealed ECM-2505 and ECM-2503, both pointing to a damaged fuel pressure sensor as a possible source of the DTC being triggered; however, there are other potential causes as well.

Of the two DTCs, I suppose ECM-2503 is the key DTC to pay attention to as fuel is cut off when it is triggered (ECM-2505 only 'reduces' fuel).

From VIDA:

Diagnostic trouble code (DTC) ECM-2503 is stored if the fuel pressure is too low in relation to the signal transmitted to the fuel pressure valve.

Possible source

• The car has been driven until the tank is empty
• Air in the fuel
• Blockage or leakage in the fuel supply
• Blocked fuel filter
• Damaged fuel pressure sensor
• Faulty pressure safety valve
• Damaged fuel pressure control valve
• Damaged fuel pump

It's probably time to start replacing parts now...

In the meantime, if anybody has any insight on the below, I would appreciate the advice:

• On VIDA, a live read of the "current through fuel pressure regulator valve" can be obtained. Can anybody point out to where this pressure regulator valve is? Is it the one on the HP pump? I have yet to look on VIDA, but are there nominal/reference values for it?
• Where are these so-called pressure control and/or safety valves? Are they within the HP pump assembly itself? Or are they external to it?
• Any thoughts on why it only happens (so far) once the engine has well reached its operating temperature and not on warm-up?