OBD Code P2402: EVAP Leak Detection Pump Control Circuit High

Quick Answer

What Is OBD Code P2402?

The P2402 diagnostic trouble code indicates that your vehicle’s onboard diagnostic system has detected a voltage condition that is higher than expected in the EVAP (Evaporative Emission Control System) leak detection pump control circuit. This code is part of the emissions monitoring system and signals that the pump isn’t receiving the correct electrical signal from the engine control module (ECM).

The EVAP leak detection pump is a critical component that helps your vehicle detect fuel vapor leaks in the fuel system and charcoal canister. When the ECM detects abnormal voltage in the control circuit—specifically voltage that’s too high—it stores the P2402 code and illuminates the check engine light.

What Does P2402 Mean?

P2402 is a manufacturer-specific code that breaks down as follows:

• P = Powertrain system code
• 2 = Emissions control system
• 4 = Auxiliary emissions control system
• 02 = EVAP leak detection pump control circuit high

The “control circuit high” designation means the ECM is detecting a voltage level that exceeds the normal operating range for the pump’s control circuit. This could indicate an open circuit, a short to voltage, a faulty pump, or a problem with the ECM itself.

The EVAP leak detection pump works by pressurizing the fuel system to detect small leaks. When the circuit voltage is abnormally high, the pump may not operate correctly, preventing the vehicle from properly monitoring for fuel vapor leaks. This can result in failed emissions tests and potential fuel odors.

Common Symptoms

Drivers experiencing P2402 may notice:

• Check engine light illuminated on the dashboard
• Fuel smell near the fuel door or under the vehicle
• Difficulty passing emissions inspection
• No noticeable drivability issues (the vehicle may run normally)
• Intermittent check engine light that comes and goes
• Hissing sound from the fuel tank area during refueling
• Reduced fuel economy in some cases

Possible Causes (Ranked by Frequency)

1. Faulty EVAP Leak Detection Pump – The pump itself may be failing or have an internal electrical fault, causing it to draw excessive current or present high resistance to the control circuit.
2. Wiring Harness Issues – Corroded, damaged, or pinched wires in the pump control circuit can cause voltage irregularities and signal the “circuit high” condition.
3. Loose or Corroded Connectors – Poor electrical connections at the pump connector or ECM connector can create resistance and voltage spikes.
4. Engine Control Module (ECM) Malfunction – A faulty ECM may incorrectly interpret the pump circuit voltage or fail to properly control the pump output.
5. Short to Voltage in the Wiring – The pump control circuit may be shorted to a positive voltage source (battery or ignition voltage), causing the circuit to read high.
6. Faulty Relay or Control Module – The relay that controls power to the pump may be stuck or malfunctioning, preventing proper voltage regulation.
7. EVAP Canister Issues – While less common, a faulty canister or purge control valve can affect the pump circuit indirectly.

Diagnostic Steps

Follow these steps to diagnose P2402:

Step 1: Scan for Additional Codes

Use a quality OBD-II scanner to check for other codes that may be stored alongside P2402. Related codes like P2401, P2403, or P2404 can provide clues about the root cause.

Step 2: Inspect the EVAP Pump Connector

Locate the EVAP leak detection pump (usually near the fuel tank) and inspect its electrical connector for:

• Corrosion or green/white deposits
• Loose or bent pins
• Water intrusion or moisture
• Proper seating in the connector

Clean the connector with electrical contact cleaner if corrosion is present.

Step 3: Check the Wiring Harness

Visually inspect the pump control circuit wiring for:

• Cuts, abrasions, or pinched wires
• Signs of water damage or corrosion
• Proper routing away from heat sources
• Loose connections at the ECM end

Step 4: Test Voltage with a Multimeter

With the key on (engine off), use a multimeter to measure the voltage at the pump connector:

• Normal operating voltage is typically 0-12 volts depending on the vehicle
• If voltage is consistently above the normal range, suspect a wiring short or ECM issue
• Test both the control signal wire and ground connections

Step 5: Check the Pump Ground Connection

Verify that the pump has a solid ground connection:

• Inspect the ground wire for corrosion or looseness
• Test continuity from the pump ground to the battery negative terminal
• Poor ground connections can cause voltage reading anomalies

Step 6: Test the Pump Resistance

Disconnect the pump connector and measure the pump’s internal resistance with a multimeter (typically 20-50 ohms depending on the vehicle). If resistance is extremely high or infinite, the pump is faulty.

Step 7: Consult the Service Manual

Refer to your vehicle’s specific service manual for exact voltage specifications, connector pin assignments, and testing procedures, as these vary by manufacturer.

Repair Cost Estimates

Typical repair costs for P2402 vary depending on the underlying cause:

• Connector Cleaning/Repair: $50 – $150 (DIY possible)
• Wiring Harness Repair: $150 – $400 (labor-intensive)
• EVAP Leak Detection Pump Replacement: $300 – $800 (parts + labor)
• ECM Reprogramming: $200 – $500
• Full ECM Replacement: $1,000 – $2,500 (rare)

Most P2402 repairs fall in the $300 – $600 range when the pump needs replacement. Diagnostic fees from a dealership typically run $100 – $150.

Can I Still Drive?

Yes, in most cases you can continue driving with P2402 active. This code does not typically affect engine performance, drivability, or safety. Your vehicle will run normally and you won’t experience loss of power or stalling.

However, you should address this code soon because:

• You will fail emissions testing until the code is resolved
• The check engine light will remain illuminated
• Fuel vapor leaks may go undetected, potentially creating a fuel smell
• In some regions, driving with an active check engine light may result in fines

Severity: Moderate. While not an emergency, this is an emissions system fault that should be diagnosed and repaired within a few weeks to avoid failing an inspection or incurring penalties.

Frequently Asked Questions

Q: What’s the difference between P2402 and P2401?

A: P2401 indicates the EVAP leak detection pump control circuit is LOW (insufficient voltage), while P2402 indicates it’s HIGH (excessive voltage). Both codes point to problems with the pump’s electrical control circuit, but they suggest different root causes. P2401 often indicates a pump failure or open circuit, while P2402 typically suggests a short to voltage or wiring issue.

Q: Can I clear P2402 myself?

A: You can clear the code using an OBD-II scanner, but this is only a temporary fix. The code will return if the underlying problem isn’t resolved. Clearing the code without repairing the issue means you’ll fail emissions testing and the check engine light will come back on after a few drive cycles.

Q: Is the EVAP leak detection pump the same as the charcoal canister?

A: No. The EVAP leak detection pump is a separate component that pressurizes the fuel system to test for leaks. The charcoal canister stores fuel vapors. Both are part of the EVAP system, but they serve different functions. P2402 specifically relates to the pump, not the canister.

Q: Will P2402 cause my check engine light to stay on permanently?

A: Not necessarily. Some vehicles may display an intermittent check engine light if the fault is intermittent (such as a loose connector that only makes poor contact occasionally). However, once the fault is detected, the code is stored and the light will typically remain on until the problem is fixed and the code is cleared.