Wrong repair

Tiny
GABOCA
  • MEMBER
  • 2011 BMW 535I
  • 3.0L
  • 6 CYL
  • RWD
  • MANUAL
  • 67,000 MILES
A check engine light came on two weeks ago. The car drove fine, but the light stayed on so I took it to the shop and they said it was the fuel tank vent valve that needed to be changed. Just a week later the car stalled and it gave a message of drive train malfunction, maximum output not available. The check engine light also came on. I took it to a different shop this time. They said the problem is the rail fuel pressure sensor. Is it possible that they replaced the wrong part the first time around and I payed for a repair that wasn't the solution to the problem?
Wednesday, May 31st, 2017 AT 12:36 PM

1 Reply

Tiny
STEVE W.
  • MECHANIC
  • 14,053 POSTS
Two unrelated failures. The fuel tank vent valve is part of the EVAP (emissions) system. It opens/closes to remove excess fuel vapor from the vent canister and test the EVAP system.

The fuel rail pressure sensor on the other hand is part of the system that controls the fuel pressure the engine runs at. It sends a signal to the ECM which then uses that along with other sensor data to control the fuel pump driver module which varies the fuel pump speeds in order to regulate fuel delivery based on what the ECM thinks the engine needs.
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Wednesday, May 31st, 2017 AT 3:21 PM

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