2004 V70 2.4 non-turbo, 65K miles. Recently the "Check Engine" light came on then off and then on, etc. I checked the codes and it was "Fuel Rail Pressure Sensor - Low voltage". Called my local dealer as Recall 181 covers this. They replaced the part in about 20 minutes or so.

As I started the car, right away I noticed the fuel pump buzzing, loudly. I told the service advisor but his response was he doesn't hear anything. I walked him to the back of the car, and then he admitted to hearing it. They pulled it back in and said it was the fuel pump and that it was making that noise when I brought it in. Clearly, it wasn't. I shook my head and walked away as it was obvious they were not willing to do anything about it.

The noise is a loud buzzing noise coming from the back of the car. It is very audible when the car is just ideling. Also when I put the key into position II, which inturn primes the fuel pump, it sounds like a grinding noise. It does it every time and the noise is exactly the same (with a full tank of gas)

My question are:

1. What exactly could have happened as a result of them replacing the Fuel Rail Pressure Sensor?
2. Is this part the same thing as a fuel pressure regulator? If not, what exactly does it do?
3. What can I check to make sure the fuel system is working properly?

Thank you,
-Adrian

 

I have never seen this before. As far as I know the sensor they replaced is on the end of the fuel rail.

I would take it back again and talk to the Service Manager.

 

I called them and they said there is nothing they can do other then replace the fuel pump at my expense.

The dealer, as do I, suspect the noise is coming from the in-tank fuel pump. On that note, what is the most common reason fuel pumps get noisy or go bad?

 

Just because a fuel pump is noise dosen't mean it is bad or going bad...well...on my 745t, they are both, the intake and main fuel pumps, really loud all the time.

 

It usually gets louder with age. If it were me I would run it till it died then replace it.

 

Right, however for years it has had a low volume high pitch whine. Then after recall 181, perhaps by coincidence, it now sounds like a loud buzzing.


This is my wife's car, and I would prefer for her not to get stranded for one. She also finds it very annoying as you can hear it while driving.

 

I know what you mean wagons are always the worse as far as noise from the pumps.

Not sure how much the sensor messes with fuel pressure.

I would think the only fix would be a new pump. Not sure of the 2004 is under the extended warranty for the nipples but if it was and the nipple cracked that would be one way to get it free.

 

Now I'm getting a new code P0172- Fuel trim bank one condition.

Any ideas?

 

Not right off hand let me dig and see what I can find.

 

Since this code really doesn't give any specific information and the car has 64K miles I decided to replace the spark plugs today. I picked up some new ones from the dealer and installed them and reset the code.

The old ones actually looked really worn out at 64K, the tips were just barely sticking out. Otherwise they looked OK. We'll see how soon the code comes back.

 

Same code P0172 came back the same day after about 12 or so miles.

 

That is either a vacuum leak or the Mass Flow sensor going bad.

 

Could the fuel pump be over pressuring the fuel system?

 

Maybe if the new sensor is bad.

 

Can you give me the details on what the pressure should be at idle, etc?

 

380KPA or about 55 PSI.

 

I was told that this sensor only monitors fuel pressure and doesn't do anything to actually control it in any way. Is this not that case?

 

Im not 100% sure.

 

Can you recommend software or a scanner device which can read Volvo codes (if it can do BMW as well, even better). I have a generic one but it's not giving any details other then the car is running rich. P0172. Thanks.

 

Some on here have spoke of them but I have never used them so I would be able to help on that one.