Does this code mean my fuel pump has failed?

Not by itself. This code describes the control circuit — the path the module uses to command the pump — rather than the pump's own condition. An open in that path means the pump is never told to run, which looks identical from the driver's seat to a pump that cannot run. The pump is the last thing in the chain and the most expensive, so it should be the last thing you conclude, not the first. Work forward from the module's output through the relay or pump control module, the wiring, and the connector at the top of the tank.

What is an inertia switch and why does it matter here?

It is a mechanical safety switch fitted in the fuel pump circuit on many vehicles that opens on a sharp deceleration and stays open until somebody presses its reset button. The reason it exists is that a pump still running after a crash can feed fuel through a ruptured line, so the whole circuit is designed to fail off. The practical consequence is that a heavy pothole, a minor car park knock or an incident a previous owner never mentioned can leave you with an open circuit and a no-start. They are usually hidden in a footwell corner, behind a kick panel or in the boot near a wheel well, and checking one takes about a minute.

There are two fuel pumps on my car. Which one is "A"?

Look it up in service data for your specific vehicle rather than assuming, because the letter identifies a channel and not a component. Direct injection engines have a low-pressure lift pump in the tank feeding a high-pressure pump on the engine. Saddle-shaped tanks have a transfer pump moving fuel between the two lobes. Some pickups have two separate tanks. The manufacturer assigns the letters deliberately in each case, and on a vehicle with two pumps, choosing the wrong one is an expensive mistake to make on an assumption.

Can I drive it while I sort this out?

It is not a good idea. Even if the vehicle is currently starting and running, an intermittent open in the fuel pump control circuit means the engine can lose fuel pressure at any moment — and that is the same as the ignition being switched off, at whatever speed you happen to be doing. The failure mode here is not gradual and gives no warning. If the car is running well enough to move, move it somewhere it can be worked on rather than continuing to use it.

OBD-II trouble code

P0627: Fuel Pump "A" Control Circuit/Open

The fuel pump control circuit is one of the few systems on a car designed around a crash rather than around convenience — the fail-safe is deliberately to stop the pump. That design decides both what this fault feels like and the order in which you check things.

High severityPowertrainFuel & Air MeteringDo not drive

Quick facts

System: Powertrain
Category: Fuel & Air Metering
Severity: High severity
Drivable: No — stop driving until repaired
Repair cost range: $90 – $1,400
DIY difficulty: Intermediate DIY

What does P0627 mean?

P0627 is the module reporting that the fuel pump 'A' control circuit is open, or is otherwise not presenting a complete and plausible path. It is the general code of the group; P0628 and P0629 name a low and a high reading in the same circuit.

The first thing to be clear about is that this is a control fault and its consequence is fuel delivery. If the module cannot command the pump, the pump does not run — and an engine without fuel pressure does not start, or stops. That is why this code sits at the serious end of the range even though nothing mechanical has broken. The realistic presentations are a no-start with healthy cranking, a stall that arrives without warning, or an intermittent version of both that gets progressively worse as the fault develops.

What makes this circuit genuinely different from the other control circuits in this part of the code range is that it was designed around a crash. Fuel pumps are the one electrical load on a vehicle where continuing to run after an accident is actively dangerous: a pump that keeps pushing fuel through a ruptured line into a hot engine bay is a fire. So the engineering priority on this circuit is not to keep it working, it is to make sure it stops. On most vehicles the module will only command the pump when it can see engine rotation, cutting it within a second or two if the crankshaft signal disappears — which is why the pump does not run continuously with the key on. Many vehicles add a mechanical inertia or impact switch in the circuit that opens on a sharp deceleration and stays open until somebody presses its reset button.

That design has two practical consequences and both are useful. The first is that the fail-safe direction is off, so any fault the module cannot make sense of results in no fuel rather than in fuel it cannot control — which is safe, and which is why an electrical fault here presents as an engine that will not run rather than as one that runs badly. The second is that the crash-safety hardware is part of the circuit and is a genuine source of this code. Inertia switches get tripped by potholes, by minor car park impacts, and by previous incidents nobody mentioned, and once tripped they are simply an open circuit. They are usually tucked into a footwell corner, behind a kick panel or in the boot near a wheel well, and checking one takes a minute. It is a poor use of an afternoon to trace a circuit back to a switch that only needed pressing.

Before any part is ordered, work out what the letter means on your vehicle. 'A' identifies a channel, not a component, and it does not automatically mean the main in-tank pump. Vehicles with two pumps assign the letters deliberately: a direct injection engine has a low-pressure lift pump in the tank feeding a high-pressure pump on the engine, a saddle-shaped tank has a transfer pump moving fuel between its two lobes, and some pickups have two tanks. Service data will tell you which is 'A'. Guessing is how people drop a tank for nothing.

The other structural question is what sits between the module and the pump, because it varies more than people expect and every junction is a place an open can hide. It may be a simple relay in the underbonnet fuse box. It may be a dedicated fuel pump control module, which on many vehicles is mounted low at the rear where it collects road spray and salt. On some designs the command passes through a body or gateway module before it ever reaches the pump circuit. Map that chain first and then test at each junction, rather than testing at the pump and working blindly backwards.

One quick test is worth doing before anything else because it costs nothing and changes the whole approach. Turn the ignition to run without cranking and listen at the open fuel filler: on most vehicles the module runs the pump for about two seconds to pre-pressurise the rail. Hearing it means the control path completed at least once, which points at something intermittent or load-related. Hearing nothing is consistent with the circuit this code describes, and tells you to start at the switching element rather than at the pump.

Treat the vehicle as one that may stop without warning. Even where it is currently starting and running, an intermittent open in this circuit means the engine can lose fuel pressure at any speed, and losing power in traffic is a safety problem regardless of how healthy the rest of the car is.

Common causes

Tripped inertia or impact cut-off switch that has not been reset
Open in the fuel pump control wire between the module and the switching element
Failed fuel pump relay or heat-damaged relay socket terminals
Failed fuel pump control module, often corroded from underbody exposure
Fuel pump module connector at the top of the tank unlatched or with a backed-out terminal
Blown fuse in the fuel pump supply or control circuit
Corroded ground for the fuel pump circuit at the rear of the vehicle
Chafed harness where the fuel pump wiring crosses the underbody or a suspension mount
Failed module output driver for the fuel pump control channel
Rodent damage to the wiring running along the underbody to the tank

Symptoms

Engine cranking normally but never starting
Engine stalling without warning and refusing to restart
No two-second pump prime audible when the ignition is switched on
Long cranking before the engine catches
Sudden loss of power at speed as though the ignition had been switched off
Engine starting and running for a few seconds before dying
Check engine light stored alongside fuel pressure or misfire codes
Intermittent no-start that appears more often after rough roads

Diagnostic steps

1.Do the prime test first, because it is free and it splits the diagnosis. Turn the ignition to run without cranking and listen at the open fuel filler, or have somebody listen while you switch on. On most vehicles the module commands the pump for roughly two seconds to build rail pressure before you crank. If you hear it, the control path completed at least once and you are looking at something intermittent or load-related. Silence points at a control circuit that is not completing at all, and that is what this code describes.
2.Establish which pump 'A' refers to on your specific vehicle before you buy anything. The letter is a channel identifier, not a synonym for the main pump. Vehicles fitted with two pumps — an in-tank lift pump feeding a high-pressure pump on a direct injection engine, a transfer pump in the second lobe of a saddle-shaped tank, or a dual-tank arrangement on a pickup — assign the letters deliberately. Look the mapping up in service data. Replacing the wrong pump on a vehicle with two of them is one of the more expensive assumptions available.
3.Work out what sits between the module and the pump on your vehicle, because the architecture varies and it determines where an open can hide. Some vehicles use a simple relay in the underbonnet fuse box. Some use a separate fuel pump control module, frequently mounted low at the rear of the vehicle where it is exposed to water and road salt. Some drive the pump through a body or gateway module. Identify the chain, then test at each junction rather than guessing.
4.Check the inertia or impact cut-off switch if your vehicle has one, and check it early. This circuit carries a deliberate crash-safety interruption on many vehicles: a switch that opens on impact and stays open until it is manually reset. It can be tripped by a heavy pothole, a minor car park knock, or a previous owner's incident, and once tripped it is an open circuit that no amount of testing further downstream will explain. They are commonly hidden in a footwell corner, behind a kick panel or in the boot near the wheel well.
5.Inspect the fuel pump module connector at the top of the tank, which on most vehicles means lifting the rear seat base or the boot floor to reach an access hatch rather than dropping the tank. Look for a terminal that has backed out, a connector that was not fully latched after previous work, and any sign of heat at the terminals. This is the single highest-yield physical inspection on the circuit and on most vehicles it takes ten minutes.
6.Test for supply and ground at the pump connector with the ignition in the prime window, and test the module's control leg separately with the relay or driver removed. Those two measurements together tell you whether the break is upstream of the switching element, in the switching element itself, or downstream in the run to the tank — which is three very different jobs.
7.Do not overlook the fuse and the relay socket. A relay that has been swapped out and a fuse that has been replaced still leave a socket behind, and heat-damaged or spread socket terminals produce an intermittent open that returns within weeks. Look for browning around the terminals specifically.

Repair cost

$90 – $1,400

Diagnosis is $90 to $200. The outcomes vary enormously and the cheap ones are real: resetting a tripped inertia switch costs nothing but the diagnostic time, and a fuel pump relay is $15 to $90 with minutes of labour. Repairing a corroded connector at the top of the tank or a damaged section of underbody harness is $120 to $400, mostly labour. A fuel pump control module is $120 to $600 fitted, and on vehicles where it is mounted low at the rear it is a common failure worth checking before anything is removed. A complete in-tank fuel pump module is $350 to $1,100 fitted depending on whether the tank has an access hatch or has to be dropped — but note that this code describes the control circuit, so the pump itself is only the answer when testing has actually reached it. If the module's own output driver has failed, control module replacement and programming is $450 to $1,400.

Estimate your repair

Run the numbers for your vehicle

Open the Repair Cost Estimator with fuel pump replacement preselected. Adjust labor rate and vehicle category to fit your situation.

Estimate your repair cost

DIY vs shop

This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.