P008C — Fuel Cooler Pump Control Circuit Open

P008C — Fuel Cooler Pump Control Circuit Open. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: poor ground connection, open or shorted wiring in the circuit, corroded, loose or damaged connector.

powertrain (engine/transmission)

Is it safe to drive?

Drive cautiously if fuel pressure remains stable P008C identifies an open fuel cooler pump control circuit. If the engine runs normally and fuel pressure or temperature remains stable, a short trip may be possible, but the fault should be repaired promptly. Stop driving if a fuel-pressure warning appears, the engine stalls, runs severely rough, or fuel temperature rises.

Typical symptoms

The check-engine light may illuminate while P008C is stored as a confirmed or pending code
The fuel cooler pump may not run when the engine requests cooling circulation
A commanded-on pump with no detected current or feedback may be visible in scan data on supported vehicles
On fuel systems dependent on this pump, low fuel pressure, hard starting, rough idle, hesitation, or stalling may occur
A fuel-temperature warning may appear on vehicles that monitor fuel-cooling performance

Common causes

An open, chafed, or broken wire in the fuel cooler pump power or control circuit
A corroded, loose, or water-contaminated connector at the fuel cooler pump, relay, or control module
An open winding inside the electric fuel cooler pump motor
A failed high-side driver, relay, or fuel cooler pump control module
A blown fuse or fusible link supplying the fuel cooler pump circuit
A high-resistance or open ground connection on the pump or control module

How to diagnose with an OBD scanner

Confirm P008C with an OBD2 scanner Connect an ELM327 adapter and use AIScanAuto, or another OBD2 scanner, to read confirmed, pending, and permanent codes. Record P008C freeze-frame data, including fuel pressure, fuel temperature, engine speed, and pump-command information when supported. Clear the code only after saving the data.
Inspect the pump and wiring With the ignition off, inspect the fuel cooler pump, connector, control module, and nearby harness for corrosion, heat damage, chafing, water intrusion, or separated pins. Also check whether the connector is fully seated and locked.
Check protection and grounding Using the vehicle wiring diagram, identify the circuit's fuse, fusible link, relay, and ground points. Confirm fuse integrity, relay operation, connector pin condition, and low-resistance ground paths before condemning the pump.
Perform a commanded pump test Command the fuel cooler pump on during a key-on or active test as specified by the service information. Use a multimeter and, if available, a current clamp to verify voltage at the pump and voltage drop through its supply and ground paths. Do not assume the pump is faulty merely because it does not run.
Isolate the open circuit Follow the manufacturer circuit procedure to determine whether control is high-side or low-side. An open pump winding will show abnormal continuity or resistance, while an open supply or ground can prevent the motor from operating even when the command is present.
Repair and verify P008C Repair damaged wiring, terminals, grounds, fuses, relays, the pump, or the control module as testing indicates. Clear P008C, operate the pump, and recheck for pending codes while monitoring commanded operation, fuel pressure, and fuel temperature where available.

Approximate repair cost

Typical independent-shop estimate: $200-$800 USD for diagnosis and repair, depending on whether the fault is wiring, a fuse or ground, or the fuel cooler pump or control module. Figures are estimates and vary by region and labor rates.

Common questions

Does P008C always mean the fuel cooler pump is bad?

No. P008C reports an open control circuit, and the pump may be functioning correctly. A broken wire, corroded connector, poor ground, blown fuse, failed relay, or control-module driver can produce the same code.

Is it safe to drive with P008C stored?

It may be safe for a short distance if fuel pressure and temperature are stable and the engine runs normally. Avoid continued driving if P008C is accompanied by a fuel-pressure warning, stalling, severe roughness, overheating, or a fuel-temperature warning.

Why does P008C keep returning after the code is cleared?

Clearing the code does not repair the open circuit. P008C will return whenever the control module again detects that the fuel cooler pump circuit is incomplete, unless the wiring, connection, protection, ground, pump, or driver is corrected.

What electrical checks are most useful for P008C?

Start with the pump-command test, then verify fuse and relay operation, connector pin condition, pump voltage, and voltage drop through the supply and ground paths. These checks distinguish an open pump winding from a wiring or control-module fault.

The engine control unit logs code P008C when it detects an open circuit condition in the fuel cooler pump control system. This is not a sensor reading issue — it means the electrical pathway that powers or controls the fuel cooler pump has been interrupted somewhere between the module and the component. When the ECU sends a command or expects a signal on this circuit, it finds nothing coming back, which triggers the fault after the condition is verified during repeated key cycles.

A fuel cooler pump helps manage fuel temperature, particularly in diesel applications or high-performance engines where fuel can heat up during sustained operation. The pump draws current through a dedicated circuit, and the ECU monitors that circuit for proper operation. When the path is broken — whether through a cut wire, corroded connector, blown fuse, or failed pump motor — the module logs P008C. The code only sets after the ECU confirms the fault multiple times under specific operating conditions, which is why simply unplugging a sensor for a moment may not trigger it.

When P008C appears, the freeze frame data stored alongside it becomes your most valuable starting point. That snapshot records engine load, RPM, coolant temperature, vehicle speed, and other sensor values at the exact moment the fault was detected. Recreating those conditions during your diagnosis tells you whether you're chasing an intermittent issue or something that happens predictably at certain loads or temperatures.

Symptoms of P008C

The check engine light is the most obvious sign. Beyond that, you may notice reduced functionality of the fuel cooling system or none at all. Some vehicles enter a limited-power limp mode depending on which module controls the circuit and how severely the fault affects overall operation. Intermittent operation is common if the open condition is caused by a loose connection rather than a complete break. In rare cases, increased fuel consumption can result from the engine compensating for an unregulated fuel temperature. You might also see related codes appear simultaneously, since a wiring issue can affect multiple circuits.

Common Causes of P008C

The most frequent culprit is a wiring problem in the harness leading to the fuel cooler pump. Chafing from heat, road debris, or improper routing can eventually break a conductor inside the insulation. Connector pins are a close second — corrosion from moisture intrusion, backed-out terminals that no longer make full contact, or physical damage to the connector housing all create resistance or open circuits. A blown fuse that feeds this specific circuit will also set P008C. The fuel cooler pump motor itself can fail internally, presenting as an open winding. Poor ground connections at the pump or module end prevent the circuit from completing properly. In newer vehicles, the control module driver that switches the circuit can fail, though this is less common than harness or connector issues.

How to Diagnose P008C

Begin by connecting an OBD2 scanner and confirming P008C is stored in the powertrain control module. Record the freeze frame data before clearing anything — that information guides the rest of your troubleshooting. Next, check for any other stored codes. Related faults in adjacent circuits often point to a shared power supply or ground that is the real root cause. After documenting codes, pull up any available TSBs for your specific make and model; manufacturers sometimes issue service bulletins that describe known failures and recommended solutions for this exact code.

With the vehicle safely elevated, perform a thorough visual inspection of the fuel cooler pump wiring harness and connectors. Look for cracked insulation, rubbed-through wires, moisture residue, or greenish corrosion on the terminals. After the visual check, use a multimeter to perform continuity testing on the circuit from the control module to the pump. Check each wire individually and note any resistance that indicates a partial or full break. Wiggle the harness gently during testing — a broken wire that only fails under movement will show up as fluctuating readings on your meter.

Measure voltage at the pump connector with the circuit powered. You should see reference voltage present. With the harness disconnected from the pump, test ground continuity — the pump needs a solid path back to the ECU ground. Finally, clear the code and perform a test drive that replicates the freeze frame conditions: similar load, speed, and temperature. If P008C returns, the fault is confirmed and still active.

Repair Options and Costs

The cost to fix P008C varies widely depending on what actually failed. Wiring harness repairs or connector replacement typically run $80 to $250 depending on accessibility and whether you source the parts yourself or pay labor rates. If the fuel cooler pump motor itself is faulty, expect to pay $150 to $500 for the part plus installation labor. Control module repair or replacement is the most expensive scenario, ranging from $300 to $1,000 including diagnostic time and programming if required.

Driving Safety Verdict

P008C carries a short-term severity rating. Most drivers can continue operating the vehicle without immediate safety risk, though the fuel cooling system may be disabled or operating at reduced capacity. Prolonged driving with unregulated fuel temperature can cause performance issues or fuel system wear over time. If the vehicle displays limp-mode behavior, stalling, or warnings affecting braking or steering, address the issue immediately. Otherwise, schedule diagnosis within a week or two — catching a simple connector or wiring issue early prevents more costly repairs later.