P0627 – Fuel Pump “A” Control Circuit/Open

System: Powertrain | Standard: ISO/SAE Controlled | Fault type: Circuit/Open | Location: Designator A

Definition source: SAE J2012/J2012DA (industry standard)

P0627 is an ISO/SAE-controlled powertrain diagnostic trouble code that indicates the vehicle has detected an open circuit condition in the Fuel Pump “A” control circuit. In practical terms, the control module expected to see a valid electrical path when commanding or monitoring the fuel pump control, but it detected a circuit that appears disconnected, unplugged, or unable to carry current as intended. Because fuel pump control designs vary by vehicle (relay-controlled, module-controlled, or integrated driver strategies), the exact wiring path and monitoring logic are not universal. Always confirm the specific circuit layout, connector pinouts, and test points using the applicable service information before probing or repairing.

What Does P0627 Mean?

P0627 – Fuel Pump “A” Control Circuit/Open means the powertrain control system has identified an open (discontinuous) condition in the control circuit associated with Fuel Pump “A.” Under SAE J2012 DTC conventions, this is an electrical fault classification focused on circuit integrity rather than fuel quality or mechanical fuel system performance. An “open” may be caused by a broken conductor, poor terminal tension, corrosion at a connector, an unplugged component, or an internal open within a related control device (such as a relay coil or driver circuit), depending on vehicle design. The code indicates an electrical path problem must be verified with testing.

Quick Reference

• Subsystem: Fuel Pump “A” control circuit (fuel pump command/control path as monitored by the control module).
• Common triggers: Unplugged connector, broken wire, poor pin fit, corrosion, failed relay coil/control device, or an open in the control-module driver path.
• Likely root-cause buckets: Wiring/connector faults; fuel pump relay/control module issues (varies by vehicle); power/ground distribution problems affecting the control side; control module driver or internal fault (less common).
• Severity: Often high—may cause no-start, stall, or intermittent loss of power due to fuel pump not being commanded or sustained.
• First checks: Verify battery condition, check related fuses, confirm connectors are fully seated, inspect harness routing near heat/movement points, and check for obvious terminal damage.
• Common mistakes: Replacing the fuel pump first without proving the control circuit is intact, or checking only the pump power feed while ignoring the control/command side identified by the DTC.

Theory of Operation

The fuel pump is typically commanded by a control module using a control circuit that may energize a relay, signal a dedicated fuel pump control module, or drive an internal output stage that enables pump operation. When the module requests pump operation, it expects the control circuit to respond electrically (for example, a relay coil circuit drawing current, or a command line showing expected electrical continuity). The module may also monitor feedback information to confirm that the commanded state is achievable.

For a Circuit/Open fault, the module’s diagnostics generally look for a missing electrical path: no current flow where current is expected, an open return path, or a command/feedback circuit that appears disconnected. Intermittent opens can occur when vibration, heat, or harness movement momentarily breaks continuity.

Symptoms

• No-start: Engine cranks but does not start if the fuel pump is not being commanded on.
• Stalling: Engine may stall unexpectedly if the control circuit opens during operation.
• Intermittent start: Starts sometimes, especially after harness movement or temperature changes.
• Extended crank: Longer crank time as fuel pressure is not established consistently.
• Reduced power: Hesitation or loss of power if fuel delivery is interrupted.
• MIL on: Check engine light illuminated; additional related fuel or power distribution codes may also appear.
• Fuel pump inoperative: Pump may be silent during key-on/prime events (varies by vehicle strategy).

Common Causes

• Fuel pump “A” control circuit open due to a broken wire, pulled terminal, or damaged section of harness
• Unplugged connector or poor terminal fit at the fuel pump module, in-line connector, relay block, or control module connector
• Connector issues such as corrosion, moisture intrusion, spread terminals, bent pins, or incomplete connector seating
• Open circuit within the fuel pump relay control path (where used), including an open relay coil circuit or poor contact at relay terminals
• Open in a fuse, fusible link, or power distribution path that supplies the fuel pump control side (varies by vehicle design)
• Open ground path affecting the control circuit’s ability to complete the command path (varies by vehicle)
• Fuel pump driver module (if equipped) internal open in the command/control circuit or its connector/terminal interface
• Powertrain control module output driver circuit concern or connector/terminal issue creating an open command path (after all external circuit checks)

Diagnosis Steps

Tools that help: a scan tool capable of reading codes, freeze-frame, and data PIDs; a digital multimeter; a test light appropriate for automotive circuits; and back-probing leads. A wiring diagram and connector end views from service information are essential because fuel pump control architectures vary by vehicle. Basic hand tools for relay/fuse access and harness inspection are also useful.

1. Confirm the code and capture context: Scan for DTCs and record freeze-frame data. Note any related fuel pump, power supply, or module communication codes. Clear the code and see if P0627 returns immediately (key-on) or only during crank/run, which helps focus the inspection.
2. Verify the complaint safely: Without guessing parts, determine whether the issue is a no-start, stall, or intermittent driveability concern. If the engine will not start, avoid repeated cranking that can overheat wiring or the starter; move directly to circuit checks.
3. Identify the exact “Fuel Pump A” control path (varies by vehicle): Using service information, determine whether the module commands the pump through a relay, a fuel pump driver module, or a direct output. Identify the control wire(s), related fuses, grounds, and intermediate connectors so you test the correct circuit.
4. Do a thorough visual inspection first: Inspect the fuel pump module connector area, relay/fuse block, any in-line harness connectors, and the control module connector. Look for an unplugged connector, broken lock, backed-out terminals, chafed insulation, or signs of moisture/corrosion. Repair obvious opens before deeper testing.
5. Check fuses and power distribution under load: Do not rely only on an ohmmeter. With the circuit commanded on (if possible), verify the relevant fuse(s) and feeds are intact and actually delivering power through the distribution points. If a fuse is open, treat it as a result and inspect for the reason before replacing.
6. Command the fuel pump on and watch data: Use the scan tool’s active test (if available) to command the fuel pump. Observe any related PIDs (command status, feedback status, or fuel pump duty/command where provided). A mismatch between command and feedback supports a control-circuit problem and helps time your measurements.
7. Test the control circuit for an open (continuity and integrity): With the system powered down as required by service information, check continuity of the fuel pump “A” control wire between the controlling module and the next device in the path (relay/driver/pump connector). If continuity is poor or absent, isolate the open by splitting the harness at intermediate connectors.
8. Perform a wiggle test to reproduce an intermittent open: While monitoring scan-tool data and/or the meter reading on the control circuit, gently wiggle the harness at common failure points (near connectors, sharp bends, and where it passes through body openings). If the circuit drops out, pinpoint the exact segment and inspect terminals for poor pin fit or broken conductors inside insulation.
9. Use voltage-drop testing to find high-resistance opens at terminals: When the circuit is commanded (or during an appropriate test state), perform voltage-drop checks across connectors, relay terminals, and suspected splice points in the control path. Excessive drop across a connector or terminal indicates a poor connection that can behave like an open under vibration or load.
10. Check relay and driver module interfaces (if equipped): If a relay is part of the design, verify the relay is being commanded and that the control side has an intact path through the relay coil and its terminals. If a fuel pump driver module is used, verify its power/ground integrity and the command/control circuit continuity at its connector before suspecting the module.
11. Evaluate the control module last: Only after wiring, connectors, power/grounds, and any relay/driver module command paths test good should you consider a control module output driver or connector issue. Confirm power and ground integrity at the module, re-check terminal tension/pin fit, and follow service information for any module-level pinpoint tests.

Professional tip: When P0627 is intermittent, focus less on “does it work right now” and more on proving circuit integrity under movement and load. Logging scan-tool data during a road test (where safe) while performing targeted harness manipulation in the shop can reveal brief command/feedback dropouts that a simple key-on test will miss.

Possible Fixes & Repair Costs

Repair costs for P0627 vary widely because the same “Fuel Pump ‘A’ Control Circuit/Open” fault can be caused by anything from a loose connector to a failed relay/driver. Final cost depends on confirmed test results, access to the component, and labor time.

• Repair or replace damaged wiring in the fuel pump “A” control circuit after confirming an open with continuity and load testing
• Clean, tighten, or replace corroded/loose terminals at the fuel pump, relay/fuse block, inertia/cutoff device (if equipped), and control module connectors
• Replace a faulty fuel pump relay (or integrated relay module) if testing confirms the control side or switched contacts are open
• Replace a blown fuse or fusible link only after identifying and correcting the underlying wiring/connector issue that caused the failure
• Repair the control module ground or power feed if voltage-drop testing shows excessive resistance affecting the pump control circuit
• Replace the fuel pump module only if command and power/ground tests prove the circuit is intact and the pump assembly cannot respond under proper supply
• Replace or repair the control module (or external driver, if used) only after verifying the output driver command is present and the circuit path is not open

Can I Still Drive With P0627?

P0627 can lead to a no-start, sudden stall, or loss of power if the fuel pump “A” control circuit is open, so driving may be unsafe or impractical. If the engine stalls, cranks but will not start, or you notice reduced power or warning indicators related to drivability, do not continue driving—have the vehicle towed and diagnose the circuit. If the vehicle seems to run normally, drive only as needed and avoid situations where stalling would be hazardous until the fault is corrected.

What Happens If You Ignore P0627?

Ignoring P0627 may result in intermittent or complete fuel pump control loss, causing unpredictable stalling, extended cranking, or a no-start condition. Continued operation with an unresolved open can also lead to repeated fault setting, reduced reliability, and potential secondary issues from repeated start attempts and unstable fuel delivery.

Related Pump Fuel Codes

Compare nearby pump fuel trouble codes with similar definitions, fault patterns, and diagnostic paths.

• P2928 – Fuel Pump Secondary Circuit/Open
• P025E – Fuel Pump Control Module Control Circuit/Open
• P2907 – Exhaust Aftertreatment Fuel Injector Circuit/Open
• P2924 – Fuel Cutoff Valve “B” Control Circuit/Open
• P2920 – Fuel Cutoff Valve “A” Control Circuit/Open
• P2868 – Transmission Hydraulic Pump Circuit/Open

Key Takeaways

• P0627 indicates an open condition in the fuel pump “A” control circuit, not a confirmed mechanical fuel system failure.
• Most verified causes are wiring, connector pin fit, relay/relay control issues, or power/ground feed problems.
• Confirm the open with test-driven checks: continuity under load, voltage-drop testing, and connector inspection.
• Replacing the fuel pump without proving the circuit path and command can waste time and money.
• If stalling or no-start occurs, treat it as a safety concern and avoid driving.

Vehicles Commonly Affected by P0627

• Vehicles using a relay-controlled fuel pump circuit monitored by the powertrain control system
• Vehicles with an external fuel pump driver module or integrated electronic pump control
• Vehicles where the fuel pump “A” circuit is routed through a fuse/relay center exposed to heat, vibration, or moisture
• High-mileage vehicles with connector terminal spread, poor pin tension, or harness fatigue near the tank or underbody
• Vehicles with recent repairs involving the fuel tank, pump module, rear body harness, or fuse/relay block
• Vehicles with added aftermarket electrical loads where wiring disturbances may affect shared grounds or power distribution
• Vehicles operated in environments that accelerate corrosion at underbody connectors and ground points
• Vehicles with safety cutoff devices (varies by vehicle) that can interrupt pump control if misadjusted or failing

FAQ

Does P0627 mean the fuel pump is bad?

No. P0627 means the control circuit for Fuel Pump “A” is detected as open. A pump can be fine while an open in wiring, a connector, a relay path, a fuse link, or a driver circuit prevents it from being commanded or powered correctly.

What is “Fuel Pump ‘A’” referring to?

“A” identifies a specific fuel pump control circuit designation used by the diagnostic standard and the vehicle’s design. Some vehicles have only one pump circuit but still label it “A,” while others may have multiple control paths; confirm the exact circuit naming and routing in service information.

Can a relay or fuse cause P0627?

Yes. An open relay coil circuit, worn relay contacts, a poor socket connection, or an open fuse/fusible link can create an open condition in the pump control path. Testing should confirm whether the open is on the control side, load side, or in the harness/connectors.

Why does the code come and go?

An intermittent open is common: loose terminals, connector fretting, harness movement, or internal relay contact issues can open the circuit only under certain vibration, temperature, or load conditions. A wiggle test and live-data logging during commanded pump operation help pinpoint intermittents.

What should be checked first for P0627?

Start with basic circuit integrity: verify relevant fuses/fusible links, inspect the fuel pump and relay/fuse block connectors for corrosion or poor pin fit, and confirm the circuit can carry load without excessive voltage drop. Only after proving wiring/connector integrity should component replacement be considered.

Always verify the exact fuel pump “A” control circuit layout and connector pin assignments in the vehicle’s service information before testing or repairs.