I'm looking for some advice on the best course of action for continuing to troubleshoot P0087 and P0088 trouble codes on my 2008 XC90. It's a 3.2L with about 140K miles on it. About a month ago the CEL came on so I used Torque for Android and my Bluetooth OBD-II module to pull the codes.

Originally it was throwing P0087 "Common rail low pressure", P0088 "Common rail high pressure", P0172 "System too rich (Bank 1)", P0175 "System too rich (Bank 2)".

I've since replaced the PEM/FCU, the 2 upstream O2 sensors, the fuel filter, and the fuel pressure sensor on the fuel rail - in that order.

The PEM/FCU had no impact, the O2 sensors seemed to have cleared the P0172 and P0175 trouble codes, and doing the fuel filter and pressure sensor my fuel pressure (through OBD-II) is now measuring about 85 PSI (up from about 60 PSI before).

At this point the only other thing that I can think of that could be causing the issue is the fuel pump itself. I'm a little hesitant in doing this since it'll be an extremely costly 'trial-and-error' part to replace.

Does it make sense that the fuel pump would be causing such high fuel pressure and is the 85 PSI I'm seeing through OBD a realistic number? It seems high to me and I'm a bit concerned it's making the vehicle dangerous to drive.

Any thoughts or suggestions from folks who may have had similar experience in troubleshooting this error codes would be greatly appreciated.

 

Are you able to read the duty cycle of the pump?

 

Hi ES6T and thank you for the troubleshoot suggestion.

I don't have VIDA/DiCE and not seeing anywhere with Torque where I can pull the duty cycle of the fuel pump. I have an oscilloscope - outside of pulling everything out of the back cargo area to get access to the fuel pump wiring is there an easier way to measure the duty cycle?

 

VIDA would make it a lot easier. But I would bet its the fuel pump. You've already guessed the other possibilities.

 

So I picked up a DiCE unit and got VIDA installed. From what I can tell I'm now within 'normal' values for the fuel system - fuel pump duty cycle is between 40-50% and fuel rail pressure is between 385-440 kPa (55-65 PSI). This is after driving the vehicle about 200 miles during the last few days - after the CEL came back on. It appears that sometime during the last 200 miles the system has gone back to normal.

I did look at the details on the P0088 code in VIDA and the fuel pressure was at 594 kPa (86 PSI), but no details on the duty cycle of the pump were recorded when the fault was thrown.

I'm at a loss right now on what I need to troubleshoot next. I may have an intermittent issue I'm dealing with - should I just clear the CEL and wait until it happens again? I've included a few images of what I'm seeing in VIDA. One thing that did seem odd is the CEM-3F90 issue for the fuel pump relay, although we've never had an issue with the vehicle not starting.

 

Hello.

Did you eventually resolve this issue? What did you find out?