The 2002 Audi A4 has a 3.0 liter V6 engine with 220 horsepower. It gets 20 miles per gallon in city driving and 29 miles per gallon on the highway. A fuel pump is not a necessary part for some cars because some engines are designed to let gravity move fuel from the tank to the engine. With nongravity designs, though, fuel has to be pumped from the fuel tank to the engine.
The fuel pump relay on a 2002 Audi A4 is behind the fuse box under the steering wheel, marked with 167.
In today's cars, the fuel pump is usually electric, and the pump creates pressure in the fuel lines by pushing the gasoline into the engine. In most cars, the fuel pump delivers a consistent flow of gasoline to the engine and unused fuel is returned to the tank.
Fuel-injected cars have an electronic control unit that prevents fuel leaking from any ruptured fuel line.
During the start, the fuel pump relay takes over to run the fuel pump. Once the engine is running, the relay shuts off. If that relay does not occur, then the car won't start. The relay also helps control fuel flow through the engine. Should the relay become broken, the extra fuel could leak out during a car accident.
As of 2009, the cost to buy a fuel pump relay for the 2002 Audi A4 is $40 to $50. It can be ordered online from an auto parts wholesaler store. A part like this would not be available over the counter at an in-person auto supply store and instead most likely can only be found online. Check with an Audi dealer because it might offer a better deal.
If you want to fix the part yourself, first remove it from underneath the dashboard. Pop open the plastic casing by prying the case apart. This process is not easy. A tool such as a flat head screwdriver should help you dig into the crevices to remove the casing.
Once its open, check for a faint burnt odor. If the smell is present, the unit has overheated.
Next, put your thumb on the relay on the circuit board and try to push it apart. It's possible the solder joints are bad and must be re-soldered. Check the contact points between the hinged and stationary part of the relay. If they're really bad, you might be able to temporarily fix them by sanding. This is only a temporary fix, though.
2002 Audi A4s are not known to have any significant issues with the fuel pump relay. If this issue is not fixed in a timely manner it could lead to engine overheating, car not starting or car catching on fire during an accident because of leaking fuel.
