P0628 — Fuel Pump "A" Control Circuit Low

OBD2 code P0628 flags a problem with the fuel delivery and mixture control (fuel pump "A" control circuit low). Short, gentle driving to a shop is usually possible. Common culprits: faulty fuel rail pressure sensor or wiring, contaminated or incorrect fuel, weak fuel pump or clogged fuel filter.

powertrain (engine/transmission)

Is it safe to drive?

Drive with caution Drive with caution. Mixture and fuel-pressure faults can cause stalling, hesitation in traffic and — when severe — catalyst damage. Avoid long trips until diagnosed.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm P0628 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the fuel delivery and mixture control for damage, corrosion, chafing or poor contact.
Subsystem check Check for supply voltage at the fuel pump "A" control connector first; then measure resistance from the signal wire to ground — near-zero ohms confirms a short to ground in the harness.
Subsystem check Measure fuel pressure at the rail and compare with factory specification at idle and under load.
Subsystem check Check short-term and long-term fuel trims in live data to see which way the mixture is off.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P0628 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P0628 (parts and labor, USD, independent shop rates): Replace the fuel filter: $80–$200; Clean or replace injectors: $200–$800; Replace the pressure regulator or sensor: $150–$450; Replace the fuel pump: $400–$900. Overall, fixing P0628 usually costs between $80 and $900. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

Is it safe to drive with P0628?

Drive with caution. Mixture and fuel-pressure faults can cause stalling, hesitation in traffic and — when severe — catalyst damage. Avoid long trips until diagnosed.

What are the symptoms of P0628?

Drivers most often notice: loss of power under load, rough idle and hesitation, hard starting or long cranking, Check Engine Light on.

How do I diagnose P0628 myself?

Start with a scan: confirm P0628, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the fuel pump "A" control, and verify the suspect component against live data before buying parts.

What does OBD2 code P0628 mean?

Will P0628 clear itself?

Sometimes P0628 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

When your engine control module detects that the voltage on the fuel pump control circuit is sitting far below specification — essentially at ground level — it logs OBD2 code P0628. This code is classified as a powertrain fault and is officially defined as "Fuel Pump 'A' Control Circuit Low." In practical terms, the PCM is telling you that it cannot properly command the fuel pump to operate, or the pump is failing to respond to its commands. The underlying problem is almost always an electrical fault somewhere in the harness, connector, or the pump assembly itself pulling that circuit down to ground potential.

Modern engines rely on an electronic fuel pump control circuit — often through a relay or a direct driver inside the PCM — to manage fuel delivery. When you crank the engine, the control module activates the pump, which then builds pressure in the fuel rail. The PCM monitors the circuit's voltage through its internal driver. If that voltage never climbs above a few tenths of a volt above ground, the module determines the circuit is shorted to ground or is otherwise unresponsive, and it sets P0628. The code typically requires the fault to be present during multiple drive cycles before it fully matures, though some implementations set it immediately on the first occurrence. When the code is stored, the PCM also captures a freeze frame — a snapshot of engine RPM, load, coolant temperature, and vehicle speed recorded at the moment the failure was detected.

Understanding how that freeze frame data relates to the fault is essential for efficient diagnosis. Reviewing the recorded conditions helps you reproduce the problem on a test drive, which is far faster than guessing blindly.

Common Symptoms of P0628

The engine loses power noticeably when you press the accelerator, particularly under heavier loads.
Idle quality deteriorates; the engine may stumble, shake, or hunt between RPM values.
Cranking takes longer than normal, and the engine may require multiple attempts before starting.
The Check Engine light illuminates and typically remains on until the fault is cleared.
Fuel economy drops noticeably compared to your vehicle's normal consumption.

What Causes P0628?

The fuel pump assembly itself has failed and is drawing the control circuit to ground.
The signal wire in the harness is chafed or cut, allowing it to short against the chassis or a ground source.
The supply voltage feeding the fuel pump control relay or driver is missing due to a blown fuse or broken wire.
Fuel injectors are clogged or leaking, disrupting the air-fuel mixture enough to mask the real electrical fault.
The fuel rail pressure sensor or its wiring is malfunctioning, causing the PCM to misinterpret delivery performance.
The fuel pressure regulator has failed, either leaking fuel internally or allowing pressure to sag.
The fuel in the tank is contaminated with water or incorrect fuel type, affecting pump operation.

How to Diagnose P0628

Plug in an OBD2 scanner and retrieve all stored codes, including P0628. Save the freeze frame data before clearing anything — this record shows exactly what engine conditions triggered the fault and guides your road test.
Look for any additional trouble codes that appeared alongside P0628. Codes pointing to voltage supply issues, sensor faults, or short circuits often reveal the root cause much faster than testing the pump directly. Check manufacturer TSB databases for your specific make and model year; many recurring P0xxx codes have documented factory fixes or PCM software updates.
Perform a thorough visual inspection of the fuel pump wiring harness and connectors, paying close attention to areas near heat sources, moving suspension components, and body passages where chafing is common. Look for broken insulation, corrosion at the connector pins, and any signs of moisture intrusion.
Test for supply voltage at the fuel pump connector with the key on and the pump commanded on. Then use a multimeter to measure resistance from the signal wire to ground — a reading near zero ohms confirms a hard short to ground somewhere in the harness.
Connect a fuel pressure gauge to the rail and compare the reading against factory specifications at idle, at cruise, and under vacuum. Both high and low pressure outside specification point toward specific failure modes that may be related.
Monitor short-term and long-term fuel trim values in the scanner's live data stream. Extreme positive or negative trims indicate whether the mixture is running rich or lean, which helps narrow the cause.
Clear the code and drive the vehicle through a complete drive cycle that includes the exact conditions captured in the freeze frame. If P0628 returns, the fault is confirmed and the system is ready for targeted repair.

Repair Options for P0628

Replace the fuel filter — $80–$200
Clean or replace fuel injectors — $200–$800
Replace the fuel pressure regulator or sensor — $150–$450
Replace the fuel pump assembly — $400–$900

Total Repair Cost for P0628

The actual cost to resolve P0628 depends entirely on which component is responsible for the low circuit condition. Parts and labor for the most common repair scenarios at an independent shop typically break down as follows: fuel filter replacement runs $80–$200, injector cleaning or replacement costs $200–$800, a failed fuel pressure regulator or sensor requires $150–$450 in parts and labor, and a complete fuel pump replacement — the most expensive scenario — typically totals $400–$900. In most cases, the total bill falls somewhere between $80 and $900. Diagnosing correctly before purchasing parts is the single most effective way to keep costs down, since the fuel pump itself accounts for the bulk of that range and should never be the first assumption.

Can You Drive with P0628?

Drive with caution. A fault in the fuel pump control circuit can lead to stalling, severe hesitation during acceleration, or an overly rich mixture that fouls spark plugs. If the fuel pressure collapses entirely, the engine will stop running — a dangerous scenario at speed or in traffic. Prolonged operation with an unresolved mixture fault can also overheat the catalytic converter. Have the code diagnosed before your next extended trip.