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2021 CLA250 Cranks But Won't Start - P0087 Fuel Pressure Low

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Robert C. · rep 0 · May 22, 4:13 AM · 1 replies · solved · Question

Vehicle: 2021 Mercedes-Benz CLA250

Hi everyone,

I'm having a major problem with my 2021 Mercedes-Benz CLA250 (C118) with about 35,000 miles. This morning, I went to start it, and it just cranks and cranks but won't fire up. A few times it sputtered and almost caught, but then died immediately. Now it's just cranking.

I managed to get a basic OBD scanner on it, and it's showing a P0087 code: 'Fuel Rail/System Pressure - Too Low'. This makes sense given the symptoms. I'm hoping it's something simple like a fuse or relay, but I'm worried it might be the fuel pump.

Has anyone else had this issue with their CLA250 or M260 engine? What was the fix? Any advice on what to check before calling for a tow?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 4:13 AM

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ClearTheCode admin answer:

The P0087 code, 'Fuel Rail/System Pressure - Too Low,' combined with a crank-no-start condition on your 2021 CLA250, strongly indicates a problem with the fuel delivery system. This means the engine isn't getting enough fuel pressure to ignite properly.

Common Causes:

  1. Low-Pressure Fuel Pump (In-Tank): This pump is responsible for drawing fuel from the tank and sending it to the high-pressure fuel pump. If it fails, no fuel reaches the engine.
  2. High-Pressure Fuel Pump (HPFP): The HPFP, located on the engine, boosts fuel pressure to the extremely high levels required for direct injection. A failure here will prevent proper fuel atomization.
  3. Fuel Pressure Sensor: A faulty fuel pressure sensor could be sending incorrect readings to the engine control unit (ECU), leading to the ECU not commanding enough fuel, or misinterpreting actual pressure.
  4. Fuel Filter: A severely clogged fuel filter can restrict fuel flow, leading to low pressure. However, this usually develops over time with other symptoms before a complete no-start.
  5. Fuel Pump Relay/Fuse: Less common, but a blown fuse or faulty relay for either the low-pressure or high-pressure fuel pump could cut power to the pump.

Troubleshooting Steps (Limited, for safety):

  1. Check Fuses: Locate and check the fuse for the fuel pump (refer to your owner's manual for the fuse box diagram).
  2. Listen for Fuel Pump: With the ignition on (but not starting), listen for a faint hum from the rear of the car (near the fuel tank) for a few seconds. This indicates the low-pressure pump is priming. If you hear nothing, it could be the pump, relay, or wiring.
  3. Professional Diagnostic: A qualified technician can perform a fuel pressure test to confirm if pressure is indeed low and isolate whether the issue is with the low-pressure or high-pressure side.

When to See a Shop:

Since your car won't start and you have a critical fuel system code, it's best to have your CLA250 towed to a Mercedes-Benz dealership or a reputable independent specialist. Diagnosing and repairing fuel system issues, especially with high-pressure components, requires specialized tools and expertise to ensure safety and proper function. Attempting to force a start or further diagnose without proper equipment could potentially cause more damage or be unsafe. They will be able to pinpoint the exact failing component and get your car running again.

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