explaining right and left fuel pumps?

2008 MERCEDES BENZ E63 AMG
170,000 MILES • V8 • 2WD • AUTOMATIC
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BHAMDOC1
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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.
Feb 1, 2026 at 9:11 AM
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STRAILER
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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.
Feb 2, 2026 at 9:21 AM
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BHAMDOC1
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Looks like the passenger side one also have a level floater not sure why
Feb 2, 2026 at 9:25 AM
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STRAILER
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They use it as differential data so they have two floats.
Feb 3, 2026 at 3:39 PM
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STRAILER
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No?
Feb 14, 2026 at 8:22 AM