Hella 004241121 Charging System Voltage Regulator

Voltage Regulation for Bosch Charging Systems

The Hella 004241121 is a 14V charging system voltage regulator built for Bosch applications that use a 12V electrical system. It regulates alternator output at 14.1 volts to help maintain stable charging performance in classic BMW and Mercedes-Benz platforms, as well as Porsche models with Bosch generator components.

Fits 1975-1998 BMW and Porsche applications, plus 1984-1993 Mercedes-Benz charging systems listed below. Part number 004241121 is a direct reference point when searching for a Bosch-restricted voltage regulator for these vehicles.

• 14V voltage regulator for Bosch alternator/generator systems
• Operating voltage: 14.1V
• Rated voltage: 12V
• Manufacturer restriction: Bosch
• Hella electrical component for charging system service

Fitment Details

• Fits 1989-1998 Porsche 911, N/A
• Fits 1991-1995 BMW 318i, N/A
• Fits 1984-1985 BMW 318i, N/A
• Fits 1992-1995 BMW 325is, N/A
• Fits 1993-1995 Porsche 928, N/A
• Fits 1985-1991 Porsche 928, N/A
• Fits 1992-1995 Porsche 968, N/A
• Fits 1988-1994 BMW 750iL, N/A
• Fits 1987-1993 BMW 325i, N/A
• Fits 1985-1993 BMW 535i, N/A
• Fits 1991-1993 BMW M5, N/A
• Fits 1988 BMW M5, N/A
• Fits 1984-1993 Mercedes-Benz 190E, N/A
• Fits 1990-1993 Mercedes-Benz 300D, N/A
• Fits 1987 Mercedes-Benz 300D, N/A
• Fits 1985 Mercedes-Benz 300D, N/A
• Fits 1986-1993 Mercedes-Benz 300E, N/A
• Fits 1988-1993 Mercedes-Benz 300TE, N/A
• Fits 1991-1992 BMW 318is, N/A
• Fits 1985-1992 BMW 735i, N/A
• Fits 1988-1992 BMW 735iL, N/A
• Fits 1988-1992 Mercedes-Benz 300CE, N/A
• Fits 1992 Mercedes-Benz 400E, N/A
• Fits 1992 Mercedes-Benz 500E, N/A
• Fits 1988-1991 BMW 325iX, N/A
• Fits 1988-1991 BMW M3, N/A
• Fits 1988-1991 Mercedes-Benz 300SE, N/A
• Fits 1988-1991 Mercedes-Benz 300SEL, N/A
• Fits 1991 Mercedes-Benz 350SD, N/A
• Fits 1990-1991 Mercedes-Benz 350SDL, N/A
• Fits 1986-1991 Mercedes-Benz 420SEL, N/A
• Fits 1986-1991 Mercedes-Benz 560SEC, N/A
• Fits 1986-1991 Mercedes-Benz 560SEL, N/A
• Fits 1984-1991 Porsche 944, N/A
• Fits 1989-1990 BMW 525i, N/A
• Fits 1985-1989 BMW 635CSi, N/A
• Fits 1987-1989 Mercedes-Benz 260E, N/A
• Fits 1986-1989 Mercedes-Benz 560SL, N/A
• Fits 1982-1988 BMW 528e, N/A
• Fits 1987-1988 BMW M6, N/A
• Fits 1987-1988 Porsche 924, N/A
• Fits 1984-1987 BMW 325e, N/A
• Fits 1986-1987 Mercedes-Benz 300SDL, N/A
• Fits 1987 Mercedes-Benz 300TD, N/A
• Fits 1985 Mercedes-Benz 300TD, N/A
• Fits 1985-1986 BMW 524td, N/A
• Fits 1985 Mercedes-Benz 300SD, N/A
• Fits 1985 Mercedes-Benz 380SE, N/A
• Fits 1985 Mercedes-Benz 380SL, N/A
• Fits 1984-1985 Mercedes-Benz 500SEC, N/A
• Fits 1985 Mercedes-Benz 500SEL, N/A
• Fits 1983-1984 BMW 533i, N/A
• Fits 1979-1981 BMW 528i, N/A
• Fits 1975-1978 BMW 530i, N/A

Common Charging Problems It Can Address

• Unstable alternator output on Bosch charging systems
• Battery charging issues caused by voltage regulation faults
• Overcharging or undercharging conditions in 12V vehicles
• Charging warning lights tied to regulator failure
• Electrical performance problems in BMW 325i, Mercedes-Benz 300E, and Porsche 944 applications

Installation Notes and Tips

Confirm Bosch manufacturer restriction before ordering, since this regulator is specified for Bosch charging components. Verify the vehicle’s charging system voltage and compare the original regulator part number, especially when servicing BMW 528e, Mercedes-Benz 190E, or Porsche 911 applications. For best results, inspect the alternator, wiring, and battery condition during replacement so the charging system can be evaluated as a whole.

This part cross-references Bosch 15005 and 15025 for the same application.

Quality Assurance

Hella supplies electrical components for charging-system service, and this regulator is built to the listed 14.1V operating specification for Bosch applications. Part number 004241121 is a focused replacement choice for vehicles requiring a Bosch-restricted 12V voltage regulator.