Ford Ecoboost no start and codes P00C6 and P025A

Diagnose and fix a Ford Ecoboost no start and codes P00C6 and P025A

When I see a Ford Ecoboost come into the shop that cranks but won’t start—or starts and stalls almost immediately—the first thing I do is scan for codes. In many cases, I find P00C6 and P025A stored in memory. These two codes almost always point to a fuel delivery issue, and understanding how they work together is key to fixing the problem correctly the first time.

P00C6 – Fuel Rail Pressure Too Low – Engine Cranking
This code indicates that during cranking, the fuel rail pressure didn’t rise to the expected level. Essentially, the PCM commanded the pump on, but the rail didn’t build pressure fast enough.

When both P00C6 and P025A appear together on a Ford Ecoboost, it’s a strong clue that the low-pressure side of the fuel system isn’t operating. The most common culprit? The fuel pump relay.

P025A – Fuel Pump Module A Control Circuit/Open,
P00C6 – Fuel Rail Pressure Too Low – Engine Cranking.

Start Your Ford Ecoboost Diagnosis with the Basics

I always begin a Ford Ecoboost no-start diagnosis the same way: check the fuel pump fuse and relay. Don’t jump to replacing the fuel pump or the control module until you’ve verified that power is actually getting to them.

1. Check the Fuel Pump Fuse— The fuel pump fuse location varies by model year and platform, so consult the correct Ford Ecoboost fuse box diagram for your specific vehicle. The fuse you’re looking for is in the Battery Junction Box under the hood.
Pull the fuse and visually inspect it. If it’s blown, replace it—but before you do, find out why it blew. A shorted pump, control module, or wiring harness could be the root cause.

2. Test the Fuel Pump Relay— On most Ford Ecoboost models, the fuel pump relay is a 4-pin micro relay. It’s a very common failure point that causes both the P00C6 and P025A trouble codes.

Here’s how I test it:

• Remove the relay from the socket.
• Using a short jumper wire, connect terminals 3 and 5 in the relay socket.
• If the engine starts and runs, the relay is faulty.
• Before replacing the relay, test the control side of the circuit:
• Terminal 1: should show battery voltage when the ignition is on.
• Terminal 2: should show a ground signal from the BCM (Body Control Module) once the PATS key is validated.
• If you see both power and ground, the BCM is working correctly and the relay itself has failed. Replace the relay, clear the codes, and your Ford Ecoboost should start normally again.

The fuel pump relay is a common failure point.

Ford Ecoboost 4-pin fuel pump relay

The fuel pump fuse location varies by model year, so refer to fuse diagrams shown here. Pull the fuse and check to see if it’s blown.

The fuse in the battery junction box provides power to the fuel pump relay contacts and control coil. The control coil is grounded by the BCM after the immobilizer passes the PATS key test. The relays close and that powers the fuel pump control module.

The fuel pump relay is a common failure point causing the Ford Ecoboost no start condition. If the fuel pump fuse is good, remove the fuel pump relay and jumper across terminals 3 & 5 in the relay socket. If the engine starts and runs, check for control coil power on terminal 1.

If you find battery voltage on terminal 1 in the socket, test for BCM ground on terminal 2 in the socket.

If the control coil is getting power and ground, and the jumper wire results in engine start, then replace the fuel pump relay.

That should solve your no-start problem.

If it doesn’t check out the operation of the fuel pump control module

How the FPCM Contributes to a No-Start

The fuel pump control module (FPCM) is an essential

Ford F1FZ-9D370-C Control Unit

component of the fuel system in the Ford EcoBoost 3.5-liter engine. The FPCM is responsible for controlling the fuel pump and ensuring that the engine receives the right amount of fuel at the right time. The FPCM is located above the spare tire on the frame of the vehicle.

The FPCM works by receiving signals from the throttle position sensor, the mass airflow sensor, and the engine coolant temperature sensor. The FPCM uses this information to determine the amount of fuel that needs to be delivered to the engine. The FPCM then sends a signal to the fuel pump to deliver the required amount of fuel to the engine.

The FPCM is also responsible for monitoring the fuel pressure in the fuel system. If the fuel pressure drops below a certain level, the FPCM will send a signal to the engine control module (ECM) to turn on the check engine light. This is an indication that there is a problem with the fuel system.

Here’s what happens behind the scenes: when you turn the key on, the BCM verifies the PATS security code, grounds the fuel pump relay coil, and powers up the FPCM. The FPCM energizes the pump for two seconds to build pressure. During cranking, the PCM watches the fuel rail pressure sensor to confirm pressure buildup.

If it doesn’t see the expected increase in pressure, it sets P00C6. If the system also detects a missing control signal in the circuit, P025A is triggered. That combination almost guarantees a Ford Ecoboost no-start or start-then-die condition.

How I Confirm Fuel Pump Control Module Failure

To confirm an FPCM fault:

• Check for battery voltage and ground at the FPCM connector.
• Verify that the control wire from the relay delivers voltage when commanded.
• If power and ground are good but the module doesn’t output power to the pump, the FPCM has failed.

Replacement modules must be programmed or initialized to the vehicle using a capable scan tool like Ford IDS, Forscan, or another high-end diagnostic platform. Simply plugging in a new module without configuration can leave the car still unable to start.

Don’t Overlook Wiring and Connectors

While rare, damaged wiring to the FPCM or corroded connectors near the rear frame can also cause P00C6 and P025A codes on a Ford Ecoboost. The rear-mounted location exposes the module to moisture, salt, and road debris. Always inspect the harness and pins for corrosion before replacing expensive components.

Final Thoughts on Diagnosing Ford Ecoboost P00C6 and P025A

When you encounter P00C6 and P025A on a Ford Ecoboost, don’t assume the high-pressure fuel pump or injectors are the problem. Start with the basics—fuses, relay, and power delivery to the FPCM. In my experience, 70% of these issues trace back to a failed fuel pump relay. The remaining cases involve a failed FPCM or corrosion-related wiring faults.

If you methodically check these components in order, you’ll fix the Ford Ecoboost no-start condition efficiently and avoid unnecessary parts replacement.

©, 2021 Rick Muscoplat