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Service bulletin GRP4/9506

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

The communication, as NHTSA indexes it (as of 2026-10-19)
TypeService bulletin
NHTSA id46404
Published by NHTSA1996-04-25
Manufacturer's numberGRP4/9506
Manufacturer's date1995-11-01
NHTSA componentSERVICE BRAKES, HYDRAULIC:POWER ASSIST:VACUUM

NHTSA's summary

EXCESSIVE OPERATING NOISE FROM THE HYDRAULIC BRAKE BOOSTER PUMP. TO REDUCE THE OPERATING NOISE FROM THE HYDRAULIC BRAKE BOOSTER PUMP, A DAMPER (ARROW, FIGURE 1) CAN BE INSTALLED BETWEEN THE PUMP AND THE BRAKE SYSTEM ACCUMULATOR.

The document

No address for NHTSA's copy can be built for this communication. Ask the dealer for it by the manufacturer's number.

Components

Brakes

Vehicles listed
PORSCHE 9111996
PORSCHE CARRERA1996

Listing a model year does not mean every vehicle of it is concerned: the document says which.

Other bulletins for the same vehicles and component
No. 1801.42022-04-05. Service bulletin. Advanced technical information for a brake squeal.
ATIALL416052021-06-28. Service bulletin. Understanding and addressing brake squeal complaints.
122-S6Q2R-062021-03-06. Service bulletin. Resubmitting at request of Mr. Bernard Hardgrave. Advanced technical information on brake fluid for all Porsche vehicles.