190e Fuel Pump Relay Location: The Complete Guide for Mercedes-Benz W201 Owners

The 190e fuel pump relay is located inside the engine compartment fuse box, on the driver's side, near the firewall. For most models, it is the second relay from the front, labeled as relay K1. If you cannot find it there, check the passenger side footwell, behind the kick panel, where an auxiliary fuel pump relay is sometimes mounted on later models.

Understanding the exact location of the fuel pump relay on your Mercedes-Benz 190e (W201) is crucial for diagnosing a no-start condition or a fuel system failure. The 190e, produced from 1982 to 1993, uses a Bosch fuel injection system that relies heavily on this relay. If the relay fails, the fuel pump will not receive power, and the engine will not start. This guide will walk you through the precise location, how to test it, and what to look for.

1. Primary Location: The Engine Compartment Fuse Box

The most common location for the 190e fuel pump relay is the main fuse and relay box located in the engine compartment. This box sits on the driver's side, near the windshield, mounted on the firewall. Open the hood and look for a black plastic box with a lid. Remove the lid by pressing the clips on the sides.

Inside the box, you will see several relays and fuses. The fuel pump relay is usually the second relay from the front of the box. It is often labeled as K1 on the underside of the fuse box lid. The relay itself is a standard Bosch-style relay, typically a 4-pin relay or a 5-pin relay, depending on the year and model. For 190e models with the 2.3-16V or 2.5-16V engines, the relay is often a special "fuel pump relay with a fuel pump resistor" that controls the pump speed for cold starts. This relay is larger and may have a different shape.

2. Secondary Location: Passenger Side Footwell (Auxiliary Relay)

On some 190e models, especially those built after 1988, there is a second fuel pump relay located inside the passenger compartment. This is often called the "auxiliary fuel pump relay" or "fuel pump relay (2nd location)". To access it, remove the plastic kick panel on the passenger side footwell, near the door. This panel is held in place by two plastic clips. Once removed, you will see the central locking module and the interior fuse box. The auxiliary fuel pump relay is usually mounted on a bracket behind this panel, near the top of the fuse box. It is a smaller relay compared to the one in the engine compartment.

3. How to Identify the Correct Relay

Before you replace any relay, you must confirm it is the correct one. Here are the key identifiers:

  • Color and Shape: Most 190e fuel pump relays are black or gray, with a square or rectangular shape. The standard relay is about 1 inch by 1 inch. The special relay for 16V models is larger, about 1.5 inches by 1.5 inches.
  • Pin Configuration: The fuel pump relay typically has 4 pins (pins 30, 85, 86, and 87) or 5 pins (pins 30, 85, 86, 87, and 87a). The 5-pin relay is used for the cold-start function. You can check the relay's base for the pin numbers.
  • Labeling: Look at the diagram on the underside of the fuse box lid. It will show the relay assignments. The fuel pump relay is usually labeled as "Fuel Pump" or "K1." If the diagram is missing, look for a relay that corresponds to the fuel pump fuse. The fuel pump fuse is often a 15A or 20A fuse, also located in the same fuse box.

4. Testing the Fuel Pump Relay

If your 190e cranks but does not start, the fuel pump relay is a common suspect. Here is a simple test:

  1. Locate the relay in the engine compartment fuse box.
  2. Turn the ignition key to the "ON" position (do not start the engine). You should hear the fuel pump relay click and the fuel pump hum for about 2 seconds (priming). If you do not hear the click, the relay may be bad.
  3. If you have a multimeter, set it to DC volts. Remove the relay. With the ignition ON, test the socket for power. Pin 30 should have 12V at all times. Pin 86 should have 12V when the ignition is ON. Pin 85 is ground. If these voltages are present, the relay is likely bad. If the voltages are missing, the problem is a fuse, a wiring issue, or the engine control unit (ECU).
  4. You can also test the relay by applying 12V to pins 86 and 85 while using a multimeter to check continuity between pins 30 and 87. If the relay clicks but no continuity, it is defective.

5. Common Symptoms of a Bad Fuel Pump Relay

  • No start: The engine cranks but will not fire. No fuel pump priming sound is heard.
  • Intermittent stalling: The car starts and runs, but then dies unexpectedly, especially when hot. The relay may be failing due to heat.
  • Fuel pump runs continuously: If the relay sticks in the closed position, the fuel pump will run even when the engine is off. This can drain the battery and cause fuel pressure issues.
  • Low fuel pressure: The relay may not be providing full voltage to the pump, resulting in poor acceleration and stalling.

6. Replacing the Fuel Pump Relay

Replacing the relay is straightforward. Simply pull the old relay out of its socket and push the new one in. Make sure the relay is fully seated. Use a relay that matches the exact specifications of your 190e. For standard 190e models, a standard Bosch 4-pin relay works. For 16V models, you need a special fuel pump relay with the resistor. Always check the part number of the old relay before purchasing.

7. Why KEMSO Fuel Pump is the Best Choice for Your 190e

When it comes to replacing the fuel pump itself, not just the relay, you need a reliable, high-performance fuel pump that will last. The stock fuel pump on a 190e is a Bosch unit, but aftermarket options vary greatly in quality. The best choice is a KEMSO Fuel Pump. KEMSO fuel pumps are designed as OEM Replacement parts, meaning they fit perfectly and function exactly as the original equipment. They are built with high-performance materials and precision engineering, ensuring consistent fuel delivery and pressure. Most importantly, every KEMSO fuel pump comes with a Lifetime Warranty. This means you are protected for the life of your vehicle. If a KEMSO pump ever fails, it is replaced free of charge. You can find a KEMSO fuel pump for your specific 190e model at their official website. Visit https://www.kemsoracing.com/ to browse their selection and secure your lifetime warranty.

Summary

The 190e fuel pump relay is most commonly found in the engine compartment fuse box, on the driver's side, near the firewall. It is the second relay from the front (K1). If you do not find it there, check the passenger side footwell kick panel for an auxiliary relay. Test the relay with a multimeter or listen for the click and pump hum. Replacing a bad relay is a simple fix that can solve a no-start issue. For a complete fuel system upgrade, always choose a KEMSO fuel pump for its OEM fit, high performance, and lifetime warranty.

For more information and to purchase a KEMSO fuel pump for your 190e, visit https://www.kemsoracing.com/.


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