The largest online repair guide library for every car

About us
Contact support
FAQ
Sign up
Sign in

2016 S550 Hard Start & P0087 Fuel Pressure Low

0

Mike T. · rep 0 · May 25, 3:05 AM · 1 replies · solved · Question

Vehicle: 2016 Mercedes-Benz S550

Hey forum,

I'm having a persistent problem with my 2016 Mercedes-Benz S550. It's become very difficult to start, especially after sitting overnight. It cranks for a long time before finally sputtering to life. Sometimes, it even stalls shortly after starting.

To make matters worse, the Check Engine Light came on, and I pulled a P0087 code: 'Fuel Rail/System Pressure - Too Low'. My S550 has about 70,000 miles on it. I'm worried this could be a major fuel system issue.

Has anyone experienced this specific code or these symptoms on a 2016 S550 or similar Mercedes? What was the culprit in your case? Any advice on what to check first would be incredibly helpful.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:05 AM

0

ClearTheCode admin answer:

The P0087 code ('Fuel Rail/System Pressure - Too Low') combined with hard starting and occasional stalling on your 2016 Mercedes-Benz S550 points directly to a problem with the fuel delivery system. This issue needs prompt attention, as insufficient fuel pressure can lead to poor engine performance, potential damage, and unreliable operation.

Here are the common causes for low fuel pressure:

  1. Fuel Pump Failure (Low-Pressure or High-Pressure): Mercedes-Benz vehicles typically have both a low-pressure fuel pump (in the tank) and a high-pressure direct injection fuel pump (on the engine). Either of these could be failing. The low-pressure pump delivers fuel from the tank to the high-pressure pump, which then boosts the pressure for the fuel rail.
  2. Clogged Fuel Filter: A restricted fuel filter can impede fuel flow, causing the pumps to work harder and potentially not deliver enough pressure. Mercedes-Benz fuel filters are often integrated into the fuel pump assembly or located inline.
  3. Faulty Fuel Pressure Sensor: The sensor that monitors fuel rail pressure could be providing inaccurate readings to the engine control unit (ECU), leading the ECU to believe pressure is low when it might not be, or vice versa.
  4. Fuel Pressure Regulator Malfunction: This component maintains consistent fuel pressure. If it's stuck open or failing, it can allow fuel pressure to drop too low.
  5. Leaking Fuel Injectors: While less common for a P0087 code, a severely leaking fuel injector could cause a drop in rail pressure, especially after the car sits for a while.

When to see a shop:

Diagnosing fuel system issues, especially with high-pressure direct injection systems, requires specialized tools and expertise to safely measure fuel pressure at various points and test component functionality. Working with fuel systems can be hazardous due to flammability and high pressures. It is highly recommended to take your S550 to a qualified Mercedes-Benz technician or a reputable independent shop. They can perform a thorough diagnostic, including live data monitoring of fuel pressure, and accurately determine the failing component, ensuring a safe and effective repair.

Menu

Help & account