P2402 Evaporative Emission System Leak Detection Pump Control Circuit High

P2402 is an OBD-II diagnostic trouble code associated with the EVAP leak detection pump control circuit. It means the engine control module (ECM/PCM) has detected an electrical condition that is higher than expected in the control circuit of the leak detection pump.

The EVAP system is designed to prevent gasoline vapors from escaping from the fuel tank and entering the atmosphere. Depending on the vehicle, a leak detection pump may be used to create pressure or vacuum in the EVAP system so the control module can determine whether the system is properly sealed.

P2402 does not automatically mean that the EVAP system has a physical vapor leak.

The word “High” primarily describes the electrical condition of the pump control circuit. The actual problem may be the pump, wiring, connector, power supply, control circuit, or another electrical component involved in operating the pump.

What the Leak Detection Pump Does

The EVAP system contains several components that work together to control fuel vapors.

Depending on the vehicle, these can include:

• Fuel tank

• Fuel filler neck and cap

• Charcoal canister

• Purge control valve

• EVAP vent valve

• Leak detection pump

• EVAP pressure sensor

• Fuel tank pressure sensor

• Connecting vapor lines

• ECM/PCM

The leak detection pump is used during an EVAP self-test.

The control module can command the pump to pressurize or depressurize the EVAP system and then monitor how the pressure behaves.

If the system cannot maintain the expected pressure, the vehicle may have a physical leak.

But with P2402, the first clue is different: the ECM is reporting a high electrical condition in the pump's control circuit.

What Does “Control Circuit High” Mean?

This is where P2402 is often misunderstood.

“High” does not necessarily mean:

• EVAP pressure is too high

• Fuel tank pressure is too high

• The pump is physically pumping too much air

• The fuel tank is over-pressurized

• There is a large EVAP leak

Instead, it generally means that the ECM sees higher-than-expected electrical voltage or another electrical condition in the leak detection pump control circuit.

For example, depending on the circuit design, a control wire could be unintentionally connected to battery voltage.

A failed component could also cause the circuit to remain electrically high when the ECM expects a different state.

The exact circuit behavior depends on the manufacturer's design.

Why P2402 Can Be Confusing

EVAP faults are often grouped together because they all involve fuel-vapor emissions.

However, there is an important distinction between:

Physical EVAP leak

Fuel vapor escapes because a hose, seal, valve, fuel cap, canister, or other component is not sealing properly.

EVAP electrical circuit fault

The ECM cannot properly control an EVAP component because its electrical circuit is malfunctioning.

P2402 belongs primarily to the second category.

A smoke test may eventually be useful, but it is not necessarily the first diagnostic step for this code.

If the pump cannot be electrically controlled correctly, proving that the vapor system is perfectly sealed will not repair the electrical fault.

Common Causes of P2402

Several problems can produce this code.

Faulty leak detection pump

The pump may have an internal electrical failure that causes abnormal current or voltage behavior in its control circuit.

The pump may still look physically intact while its internal electronics have failed.

Short to battery voltage

A control wire may have become shorted to a power source.

This can cause the ECM to detect a higher-than-expected electrical condition.

Damaged wiring

EVAP wiring is exposed to road debris, moisture, heat, vibration, and movement.

A damaged harness can develop:

• Melted insulation

• Chafing

• Broken conductors

• Pinched wires

• Incorrect previous repairs

• Corrosion

• Short circuits

Connector problems

A corroded, loose, contaminated, or damaged connector can alter the electrical characteristics of the circuit.

A pushed-back terminal may make intermittent contact or cause an unexpected electrical reading.

Incorrect component

An incorrect replacement leak detection pump or EVAP component may have different electrical characteristics from the original part.

This is especially possible when an aftermarket component is used.

Power-supply problem

The pump may share a fuse, relay, or power supply with other components.

A fault in that supply can affect the pump circuit.

Poor ground

Depending on the vehicle's design, an inadequate ground can cause abnormal circuit behavior and may produce unexpected voltage readings.

Control-side problem

The ECM may control the pump through a dedicated driver or switching circuit. A fault in that driver can potentially produce P2402.

However, the ECM should normally be considered only after the external circuit and component have been proven correct.

Symptoms You May Notice

P2402 can be surprisingly quiet from a drivability perspective.

The engine may run completely normally because the EVAP system generally does not control the basic ability of the engine to produce power.

Possible symptoms include:

• Check Engine Light

• Failed emissions inspection

• EVAP readiness monitor not completing

• Fuel vapor odor in some cases

• Difficulty completing an EVAP self-test

• Occasional EVAP-related warning messages

• No noticeable drivability symptoms

A vehicle can therefore have P2402 stored for some time without the driver noticing anything other than the Check Engine Light.

Does P2402 Mean There Is an EVAP Leak?

Not necessarily.

This distinction is particularly important.

A code such as P0456 is associated with a very small EVAP leak condition.

P2402, on the other hand, identifies a high condition in the leak detection pump control circuit.

The vehicle may have no physical vapor leak at all.

If the pump cannot be electrically controlled, the ECM may be unable to perform its EVAP test correctly. The resulting diagnostic problem can therefore exist even when all vapor hoses and fuel-system seals are physically intact.

How to Diagnose P2402 Correctly

The diagnosis should begin with the electrical circuit.

Start by scanning for all codes

Do not diagnose P2402 in isolation.

Look for additional codes involving:

• EVAP pressure

• EVAP vent control

• EVAP purge control

• Fuel tank pressure

• Leak detection

• Power supply

• Ground circuits

• Other electrical components

Another DTC may reveal a shared electrical problem.

Check the freeze-frame data

If freeze-frame information is available, examine the conditions under which P2402 was stored.

EVAP tests often occur under specific conditions involving fuel level, engine temperature, ambient temperature, and vehicle operating status.

This information can help determine when the ECM detected the problem.

Identify the Exact Leak Detection Pump

Do not assume that every vehicle places the pump in the same location.

Depending on the design, the leak detection pump may be integrated with another EVAP component or mounted near the fuel tank, charcoal canister, or another part of the vapor system.

The manufacturer's service information should be used to identify:

• Pump connector

• Power circuit

• Ground circuit

• Control circuit

• Associated pressure sensor

• Fuses and relays

• ECM connection

Inspect the Wiring

Follow the harness from the pump toward the vehicle's main wiring harness.

Look for obvious signs of damage.

Pay particular attention to areas near:

• Fuel tank

• Rear suspension

• Exhaust components

• Heat shields

• Underbody brackets

• Fuel vapor lines

Road debris can damage EVAP wiring underneath the vehicle.

A wire rubbing against a metal bracket may eventually expose its conductor and create a short to power or ground.

Check the Connector

Disconnect the leak detection pump connector and inspect it carefully.

Look for:

• Corrosion

• Water intrusion

• Bent terminals

• Loose terminals

• Pushed-back pins

• Damaged seals

• Burn marks

• Contamination

If the vehicle has been exposed to flooding, heavy rain, road salt, or underbody washing, moisture-related connector problems deserve additional attention.

Test the Control Circuit

The next step is to identify the control wire using the manufacturer's wiring diagram.

The technician should determine whether the circuit is being held at an unexpectedly high voltage.

Depending on the system, this may involve:

• Voltage testing

• Continuity testing

• Voltage-drop testing

• Short-to-power testing

• Short-to-ground testing

• Current testing

• Scan-tool actuator testing

The exact test procedure depends on the vehicle.

There is no universal P2402 control-circuit voltage that applies to every vehicle.

This is especially important with modern EVAP systems because different manufacturers use different pump and control strategies.

Use a Scan Tool to Command the Pump

If the vehicle supports EVAP leak detection pump activation through the scan tool, an active test can be extremely useful.

The technician can command the pump and observe whether:

• The pump operates

• The circuit responds correctly

• Current changes appropriately

• Pressure changes

• The pump remains electrically active when it should not

If the ECM commands the pump off but the control circuit remains electrically high, the wiring or pump electronics may require closer inspection.

Check the Pump Itself

If the wiring is correct, test the leak detection pump according to the manufacturer's procedure.

Do not simply apply battery power to an unfamiliar EVAP pump without confirming the correct procedure.

Some systems incorporate electronics into the pump assembly, and incorrect testing can damage components or produce misleading results.

The manufacturer's specifications should determine the correct resistance, voltage, current, and activation tests.

Could the EVAP Pressure Sensor Cause P2402?

A pressure sensor problem can produce other EVAP-related codes and can interfere with leak-testing logic.

However, P2402 specifically points toward the leak detection pump control circuit.

Therefore, the pump's electrical circuit should receive priority during diagnosis.

If additional pressure-sensor codes are present, the sensor and its wiring should also be investigated.

Why a Smoke Test Is Not Always the First Step

Smoke testing is one of the most useful tools for finding physical EVAP leaks.

However, P2402 is primarily an electrical circuit code.

Imagine that the leak detection pump has a shorted internal circuit.

A technician could spend considerable time smoke-testing every vapor line and finding absolutely no leak.

The electrical fault would still remain.

A better approach is:

Electrical diagnosis first → confirm pump operation → then investigate physical EVAP sealing if other evidence points toward a leak.

This avoids replacing or repairing components that have nothing to do with the actual fault.

P2402 vs P2400

These codes are closely related but describe different electrical conditions.

P2400 – EVAP Leak Detection Pump Control Circuit/Open

The ECM detects an interruption or open condition in the leak detection pump control circuit.

Possible causes include a broken wire, disconnected connector, failed pump, blown fuse, or similar interruption.

P2402 – EVAP Leak Detection Pump Control Circuit High

The ECM detects an electrically high condition in the control circuit.

A short to voltage, faulty pump electronics, incorrect wiring, or a control-side problem may produce this condition.

The distinction between Open and High changes the direction of electrical testing.

P2402 vs P2401

P2401 generally indicates a low condition in the leak detection pump control circuit.

P2402 indicates a high condition.

This means the three codes can be viewed as different electrical fault states involving the same general pump-control system:

• P2400 — Open

• P2401 — Low

• P2402 — High

The exact circuit strategy remains manufacturer-specific.

P2402 vs P0456

These codes can both appear as EVAP-related faults, but they describe very different situations.

P2402 concerns the electrical control of the leak detection pump.

P0456 indicates that the EVAP system has detected a very small vapor leak.

A vehicle can have P2402 without having a physical EVAP leak.

Likewise, a vehicle can have a genuine EVAP leak while the leak detection pump's electrical circuit is functioning correctly.

Can a Bad Fuel Cap Cause P2402?

A loose, damaged, or incorrect fuel cap can certainly cause EVAP leak-related codes.

However, it is not normally the first suspect for P2402 because P2402 is specifically associated with the leak detection pump's control circuit.

If the fuel cap is obviously damaged or incorrect, it should still be checked, but replacing it should not be treated as the guaranteed solution.

Can You Drive With P2402?

In most cases, P2402 does not create an immediate engine safety problem.

The vehicle will often drive normally because the EVAP leak detection system is primarily concerned with emissions monitoring.

Short-term driving may therefore be possible if:

• The engine runs normally

• There is no fuel leak

• There is no strong fuel odor

• No additional serious warning lights are present

However, the problem should still be repaired.

An EVAP fault can prevent emissions monitors from completing and may cause the vehicle to fail an emissions inspection.

If you smell raw fuel, see liquid fuel, or suspect a fuel-system leak, the situation is different. Fuel leakage should be investigated immediately because of the fire hazard.

Is the Leak Detection Pump Always the Problem?

No.

This is another important diagnostic distinction.

The code identifies a condition in the pump control circuit. It does not prove that the pump itself has failed.

The final repair could involve:

• Leak detection pump

• Wiring

• Connector

• Terminal

• Fuse

• Relay

• Power supply

• Ground circuit

• Control wire

• Incorrect component

• ECM driver in rare cases

The wiring and electrical circuit should therefore be tested before purchasing a new pump.

What Makes P2402 Different From a Normal EVAP Leak?

A normal EVAP leak is a sealing problem.

For example, a cracked vapor hose allows fuel vapor to escape.

P2402 is different because the control module is reporting that the electrical operation of the leak detection pump is abnormal.

The pump may not be able to perform its self-test correctly even if every vapor hose is perfectly sealed.

This is why understanding the exact wording of the DTC is so useful.

A Sensible Repair Strategy

For a vehicle with P2402, a logical diagnostic sequence is:

Scan all modules and codes.

Check freeze-frame data and EVAP-related information.

Identify the exact leak detection pump and circuit using the wiring diagram.

Inspect the pump connector and wiring.

Check for shorts to power, shorts to ground, and unwanted voltage.

Verify power and ground according to manufacturer specifications.

Test the pump with the appropriate diagnostic procedure.

Use an active test if the scan tool supports pump activation.

Check the EVAP pressure system afterward if the electrical circuit is functioning correctly.

Clear the code and perform the required drive cycle or EVAP monitor test.

This sequence is much more reliable than simply replacing the pump or performing a smoke test immediately.

Final Perspective

P2402 is best understood as an electrical control problem involving the EVAP leak detection pump.

The word “High” is the key clue: it points toward an unexpectedly high electrical condition in the pump's control circuit, rather than automatically indicating excessive EVAP pressure or a physical vapor leak.

A failed pump is certainly possible, but so are a shorted wire, damaged connector, incorrect component, power-supply problem, or control-circuit fault.

Because EVAP components are often located around the fuel tank and underneath the vehicle, wiring and connector damage should receive careful attention.

Once the electrical side has been verified, the technician can determine whether the pump itself is capable of performing the required EVAP leak-detection test. This approach avoids unnecessary parts replacement and separates a genuine pump failure from a problem elsewhere in the circuit.