The BOSCH brand Relay, fuel pump is a part installed in cars with an injection power system. Performs several functions:

1. Fuel pump control - when the ignition is turned on, the relay energizes the fuel pump for several seconds, which creates the required pressure in the system. After that, the restart of the pump will be carried out at the factory or while the engine is running;
2. Heated oxygen sensor - depending on the type of relay, heating can be turned on in several ways. This feature is not available on older vehicles;
3. Power supply to the starting injector at cold start - depends on engine settings and coolant temperature. This injector works for the same time as the starter.

The design of the fuel pump relay

It is a standard device for a relay, placed in a plastic case in the shape of a cube. Has several pins with markings. They are connected to the fuel pump, the controller, to the wires of the injectors and the battery. Depending on the car model, it can be located in the fuse box under the hood, in the injection control unit or under the dashboard.

1. SL (R129)
2. C-CLASS (W202)
3. C-CLASS Saloon (W202)
4. CLS (C218)
5. CLS SEDAN GRANDE (C218)
6. S-CLASS (W221)
7. S-CLASS Saloon (W221)
8. C-CLASS T-Model (S204)
9. G-CLASS (W463)
10. G-CLASS SUV (W463)
11. E-CLASS (W210)
12. E-CLASS Saloon (W210)
13. C-CLASS T-Model (S202)
14. C-CLASS Break (S202)
15. E-CLASS T-Model (S210)
16. E-CLASS Break (S210)
17. C-CLASS T-Model (S203)
18. R-CLASS (W251, V251)
19. M-CLASS (W166)
20. M-CLASS SUV (W166)
21. See more in applications

Like any electrical element, this node is vulnerable to breakdowns. Many car owners do not pay attention to the relay, as they are more concerned about the breakdown of other parts of the fuel system.