Hello!
I am new to this group and need help. I recently had ignition coils and spark plugs replaced after my 2011 XC70 died and would not start. They said the wires were "fried" and you could definitely smell burning plastic. A few days later, check engine light came on. The code was P0091 for fuel rail pressure sensor. Car was running fine. the light went off the next day. I called the dealer and they said not to worry about it if the car was running and starting OK. They said their would be warning signs, "hard starts,etc", of the sensor was starting to fail.
Last week the check engine light came back on. The code was again for fuel rail pressure sensor. The car was starting and running fine, but I decided to replace the sensor just in case, just to be safe.
The dealer replaced the sensor. About an hour after picking the car up, it died and would not start. It would crank but not turn over. The car had been running fine prior to replacing the fuel rail sensor.
The dealer towed the car and after looking at it for a couple days is telling me the fuel pump needs to be replaced.
They said it was probably just a coincidence the fuel pump went out after replacing the sensor.
I don't believe in coincidence and am wondering if it was something hey could have done? They said it was also possible the fuel pump was bad and the sensor was fine? In that case, they would not charge me for replacing the sensor.
I asked if it was possible it could be a wiring problem, fuel line, etc. They said they wont know for sure until they take out the fuel tank. They are quoting me $2600 to replace the fuel pump!

I find it very odd that with the exception of the check engine light coming on and (then going off), the car was running fine, until they worked on it and replaced the fuel rail sensor.

Please help! Your expertise and advice would be greatly appreciated! Thanks!

 

there's a few parts in play here: Fuel pump, fuel pump control (driver) module, Fuel pump relay and the fuel pressure sensor. Given your problem appeared and disappeared, I'm wondering if the pressure sensor was not the issue in the first place and the pump or pump controller decided to present its issue again. Talk to the service manager about what they are seeing when doing a scan via VIDA DICE. They should be able to know if the pump is active (it only takes about 25 PSI to start the car and then the computer will the the control module to increase the pressure to 50+ PSI as demand requires.) If you are getting 0 PSI at the rail, then I'd discount the pressure sensor as the issue.

 

Thanks for your reply! He is now saying the sensor may not have been the issue, but it is the fuel pump.
He didn't mention anything about a scan. He is now telling me that they will have to take the gas tank out to see what the problem was,(if it was the fuel pump, wiring issue, etc). I will relay your information to him.

 

most dealers follow the VIDA guidance on how to diagnose a problem but sometimes common sense leaves the room when they do that so you may want to get a second opinion or a press the service manager to explain how they diagnose the problem at hand. Case and point - on my VW, I had an odd thing where the alternator would cut out on very cold days. If I stopped the car, shut off and restarted, the alternator would start working again. Took it to a dealer who said there was too much resistance in one of the wire harnesses and say the factory recommended a replacement. Went to a second dealer who say "oh there's a relay in the voltage regulator that keeps the alternator from overcharging the battery that is sticking, you need a new voltage regulator". That made sense to me since shutting off the car effectively resets the relay so the voltage returned to normal. Got a new alternator and problem solved. Sorry to say VWs have the voltage regulator built into the alternator unlike many volvos where the regulator can be can be replaced separate from the alternator unit. Bonus points to Volvo here since I'd bet about half of alternator failures are regulator related not the bushings/bearings etc.