Explaining right and left fuel pumps?

Tiny
BHAMDOC1
  • MEMBER
  • 2008 MERCEDES BENZ E63 AMG
  • V8
  • 2WD
  • AUTOMATIC
  • 170,000 MILES
Can you explain to me what is the right pump under the rear seat, compared to the left side? What does each do? These are common to g bad so if the fuel rail sensor does not clear the p2542 its most likely the pump is weak, but getting conflicting reports to which could be bad and what each does.
Sunday, February 1st, 2026 AT 9:11 AM

3 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,852 POSTS
Sure, when the mains pump fails (right side) you get the P2542 Fuel Pressure Sensor Circuit - Implausible Pressure

Right Side (Passenger) - Primary Fuel Pump Module - Supplies fuel to engine rail

Left Side (Driver) - Transfer / Sender Module - Moves fuel to right side + fuel level reading

After replacing the right side fuel pump be sure to clear the codes.
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Monday, February 2nd, 2026 AT 9:21 AM
Tiny
BHAMDOC1
  • MEMBER
  • 177 POSTS
Looks like the passenger side one also have a level floater not sure why
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Monday, February 2nd, 2026 AT 9:25 AM
Tiny
KEN L
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They use it as differential data so they have two floats.
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Tuesday, February 3rd, 2026 AT 3:39 PM

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