Here is the background, it is a 2005 XC70 with 191,xxx miles.


Seven months ago I replaced the fuel pressure sensor due to loss of power and misfire issues, the car did not throw a code at that time. All was good up until about a month ago, the same symptoms came back, but this time a P0089 code.


So I replaced the sensor again, and the fuel filter, it did not help. When I checked the fuel pressure it was 43 PSI, so I replaced it with a new Bosch fuel pump, and it still would act like it was running out of fuel.


The PEM module is still in the original location and looked like crap, and it had corroded contacts, I replaced it with a used unit making sure it has good contact, and still it has issues.


Now when I start it up checking fuel pressure with both a scan tool and gauge it starts out at 58 PSI and slowly drops to 46 PSI, and I eventually get a P0089 code again.


I have checked the plugs and coil packs, they are all good.


I am at a loss as to what to look at next.


I left the pressure gauge on the fuel rail overnight and it is still holding 24 PSI, so I am ruling out any leaky injectors or a bad check valve in the fuel pump.


I am now leaning to a bad used PEM module, does anyone know how to test the module?