continued issues with fuel delivery system

I have had VW replace the in-tank fuel pump and the high pressure fuel pump, change the fuel filter and even had to return to have another VW dealer bleed the fuel system...5-6 weeks, 3 trips to 2 different VW dealership service departments and $1300 plus dollars later and I still get an intermittent "squiggly" logo blinking and intermittent check engine logo light with loss of power when driving. After the fixes and fuel pump fixes, the car would work for approximately 3-5 days prior to the light coming back on. Once the light comes on and blinks, it may stop after the car has been parked and off, or it may not. I'm a bit tired of all the issues unresolved following service from the dealer. The high pressure fuel pump was covered under warranty however the in-tank fuel pump was not. The dealer reported the fuel pressure was normal. I have noticed an air-like sound from the undercarriage back under both rear wheels. Not certain what this is. Could air be leaking into the fuel line? Any advice? Has anyone had this problem?

you didn't say why the fuel pumps were changed or what codes are now being found. The answers to those questions matters to get a good answer.

The squiggly lines light you mention I think is the traction control. That would have nothing to do with the fuel system unless a sensor or wire was damaged while dropping the tank to change the fuel pump.

If the high pressure pump was changed for low pressure and metal in the fuel system, it should have also had the in tank pump, intermediate pump, injectors, all changed and system flushed as part of the warranty fix. good luck on getting this sorted out.

Lift the rear seat and look at the lift pump line connections. Sounds like the lines are reversed.
Post a picture, or email me,
tdi2micron@yahoo.ca
Thanks,
Andrew

May or may not be. My son's 2014 Cruze diesel was getting code/s for some time and then the center dash went squiggly I guess as you call it. I believe he was getting loss of power. He took it to were I go and had it checked out. It was the DEF tank heater gone south. Had it changed 408 bucks up here and the ex vw mechanic reset the car as needed and now runs great and the codes he was also getting cleared and didn't come back. Like I said maybe maybe not the problem????

Pretty sure the squiggly light the op mentions is the glow plug light flashing.