Mercedes fuel pump relay A0025459205 W126 260 SE 300 SE 300 SEL automatic
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Genuine Mercedes-Benz fuel pump relay A0025459205 for the S-Class W126 with automatic transmission (260 SE, 300 SE, 300 SEL).
Genuine Mercedes component · Model-year specific 09/1988 – 08/1989 · Automatic transmission version
Condition of this part
Used genuine Mercedes relay. As no test bench is available, it is sold untested. The housing shows slight storage marks, the label is fully legible, and the connector pins have a slight patina. No rust, no corrosion, no breakage.
Function and location
The fuel pump relay switches the KE-Jetronic's electric fuel pump and only enables it when an engine speed signal is present – with the engine stopped, delivery is cut off even with the ignition on. It also handles the cold-start enrichment, supplies the oxygen sensor heater, and limits engine speed at 6450/min; when this limit speed is reached, kickdown is deactivated.
It is installed in the relay and control unit carrier in the engine bay on the bulkhead, plugged in next to the overvoltage protection relay and other control relays.
How can you tell if a fuel pump relay is faulty?
- Engine does not start, because the fuel pump is not enabled
- Engine suddenly cuts out while driving
- Starting problems with a cold engine due to missing cold-start enrichment
- Oxygen sensor heater remains non-functional
Compatible vehicles
Mercedes-Benz W126 S-Class, 09/1988 – 08/1989, M103 engine, automatic transmission only, rev limit 6450/min:
- 260 SE (126.020)
- 300 SE (126.024)
- 300 SEL (126.025)
Part numbers
The original part number of this relay is A0025459205 for the automatic transmission version. For context: the manual transmission version in the same period carries the number 002 545 93 05. For the V8 models 420, 500, and 560, 002 545 33 05, 002 545 16 05, 003 545 18 05, 003 545 01 05, and 003 545 25 05 apply. Earlier W126 model years before 09/1988 use 002 545 27 05 (06/1985 – 08/1986) or 002 545 52 05 (08/1986 – 08/1988); later model years from 09/1989 use the number 003 545 17 05, and from 01/1990 003 545 24 05.
⚠ Important: compare the part number before buying
This relay is the version for automatic transmission. For manual transmission in the same period, 002 545 93 05 applies. Please compare the number of your old relay 1:1 – dealer catalogues sometimes also list the same number for the W124, W201, and R107; the model-year-specific assignment documented is for the W126.
Does not fit:
- Manual transmission version – 002 545 93 05 there
- V8 models 420, 500, and 560 – 002 545 33 05, 002 545 16 05, 003 545 18 05, 003 545 01 05, 003 545 25 05 there
- W126 before 09/1988 – 002 545 27 05 (06/85 – 08/86) and 002 545 52 05 (08/86 – 08/88) there
- W126 from 09/1989 – 003 545 17 05 there, from 01/1990 003 545 24 05
- Early M110, M116, and M117 vehicles with a square relay design
Does this part fit your car? Send us the VIN (chassis number) and model year – we'll check it for free: 0179 8991069 (Mon–Fri 8 am–6 pm) or via our contact form.
FAQ
Is the relay new or used?
This is a used genuine Mercedes relay. As no test bench is available, it is sold untested; externally it shows slight storage marks and a light patina on the connector pins, but is free of rust, corrosion, and breakage.
Does this relay also fit manual transmission?
No. The number A0025459205 is intended exclusively for the automatic transmission version. For manual transmission in the same period, the number 002 545 93 05 applies.
What's included in the scope of delivery?
The exact scope of delivery can be seen in the product photos.
Related categories: Relays, W126
KFZTeile-Thot specialises in spare parts for Mercedes classic cars. Free shipping within Germany, 60-day return policy.
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