If your Mercedes-Benz or any modern vehicle won’t start, stalls unexpectedly, or flashes the Check Engine light, you might be dealing with OBD-II code P0627: Fuel Pump Control Circuit Open. This code indicates that the Engine Control Module (ECM) cannot detect continuity in the fuel pump control circuit. Let's break down what this code means, why it happens, how to fix it, and how tools like the iCARZONE UR1000 can help.

What Is Code P0627?

P0627 - Fuel Pump Control Circuit Open means the ECM has detected an open or broken circuit in the system that controls the electric fuel pump. Without proper signal or voltage, the fuel pump cannot deliver the required fuel pressure, potentially leading to serious driveability issues.

Common Causes of P0627

• Faulty fuel pump - mechanical or electrical failure
• Corroded or damaged wiring to the pump or ECM
• Faulty fuel pump relay or control module
• Blown fuse in the fuel system circuit
• ECM malfunction - hardware or software-related

Symptoms of a P0627 Code

• Hard starting or no start
• Stalling while driving
• Poor fuel economy
• Loss of engine power or hesitation
• Check Engine Light (CEL) is on
• Whining noise from fuel tank

Diagnosing P0627 with the iCARZONE UR1000

Using a professional diagnostic scanner like the UR1000 makes the process faster and more accurate:

1. Connect the UR1000 to your vehicle’s OBD-II port (usually under the dash).
2. Scan for codes and verify the P0627 fault.
3. Read live data to check fuel pump voltage, pressure, and circuit continuity.
4. Perform system tests on relays, fuses, and wiring.
5. Review freeze frame data for conditions at the time of the fault.

How to Fix Code P0627

• Replace faulty fuel pump if not delivering pressure
• Repair or replace corroded/damaged wiring and connectors
• Replace blown fuel pump fuse
• Swap in a new fuel pump relay
• Reprogram or replace the ECM if necessary

How to Prevent P0627 in the Future

• Use high-quality fuel to reduce contamination
• Inspect and maintain your fuel system regularly
• Use tools like the UR1000 for preventive diagnostics
• Clean connectors and apply dielectric grease if needed

When to Replace the Fuel Pump

Replace your fuel pump if you notice:

• Consistently low fuel pressure readings
• Difficulty starting even after repairs
• Unusual whining noises from the tank
• Frequent stalling or sputtering under load

When to Call a Professional Mechanic

If you’ve replaced relays and fuses, checked wiring, and still see the P0627 code, your ECM or fuel pump driver module may be the root cause. These require advanced diagnostics tools and expertise—don’t hesitate to consult a certified technician.

FAQ: P0627 Code & UR1000 Scanner