P2402 - EVAP Leak Detection Pump Circuit High

P2402 - EVAP Leak Detection Pump Circuit High

What This Code Means

• P2402 is identified as EVAP Leak Detection Pump Circuit High. The Open Source repository entry translates to (Leak Detection Pump circuit high). In plain terms: the control circuit for the EVAP leak-detection pump is reporting a high (faulty) electrical condition. Source mapping: Open Source (MIT) code definitions.

Context from general sources

• OBD-II codes live in a diagnostic trouble code framework used by powertrain control systems. The EVAP system is part of the emissions-control subsystem that the PCM monitors and that is subject to OBD-II fault codes, including P-series codes tied to the EVAP system. Emissions testing guidance explains that EVAP-related codes often affect the readiness and pass/fail status of emissions testing.

What This Code Means

• The vehicle's EVAP system uses a Leak Detection Pump (LDP) as part of a pressure/leak-check mechanism. A "circuit high" fault indicates an electrical fault in the LDP control pathway (voltage/signal being higher than normal or a fault condition detected by the PCM). The Open Source code description explicitly ties P2402 to the EVAP Leak Detection Pump circuit high condition. In short: there is an electrical fault in the LDP circuit, not necessarily a mechanical leak (though a leak test could still be needed to rule out leaks).

Typical symptoms you may see

• MIL (Check Engine Light) is on with P2402 stored or pending.
• Emissions readiness may be incomplete; vehicle may fail an emissions test due to EVAP-related fault codes.
• No obvious drivability issue (many EVAP codes are non-drt/driveability), though some vehicles may show occasional rough idle or hesitation if the ECU faults during startup/shutdown cycles.
• Possible related EVAP codes (examples you might see alongside P2402): other EVAP or purge valve/vent valve codes, or generic P0x codes tied to emissions.

Most likely causes (probability guidance)

• Faulty Leak Detection Pump (LDP) or its driver/activator (stuck on, shorted, or internal failure): ~40%
• Wiring harness/connector damage, corrosion, or poor connections to the LDP or PCM (short to power, open circuit, ground fault): ~25%
• PCM/ECU input/output circuit fault or software-related issue impacting the LDP control signal: ~15%
• Other EVAP components or parasitic faults (e.g., related valves, canister issues that influence the LDP context; intermittent faults): ~10-20%
• Note: If you see P2402 alone with no other EVAP codes, the fault is most often electrical (LDP or wiring). If multiple EVAP codes are present, expect a broader EVAP-system fault pattern or harness/grounding issue.

Diagnostic Approach

1) Confirm the fault and gather context

• Verify P2402 is present and note any freeze-frame data (engine running status, fuel level, accelerated load, temperature, etc.).
• Check for related EVAP codes (P0440-P0446, P0496, etc.). If multiple EVAP codes appear, plan for a broader EVAP circuit inspection.
• Confirm vehicle year/model/application if possible, since LDP location and wiring can vary by manufacturer.

2) Visual inspection and basic integrity checks

• Inspect the EVAP leak-detection pump and its wiring harness for signs of damage, chafing, heat damage, or disconnection at the connector(s).
• Check for corrosion on pins, bent terminals, or loose connectors. Reseat and reseal as needed.
• Inspect the LDP mounting for vibration damage and ensure it is securely mounted.
• Inspect nearby wiring for heat sources or grounding issues that could affect the LDP control circuit.

3) Baseline electrical checks (LDP circuit)

• With the ignition on (key in run position, engine off unless the test requires engine on), measure the LDP control circuit voltage at the connector:
  • Verify there is a proper supply voltage when the LDP is commanded on (refer to the vehicle's service data for expected voltage range and test conditions).
  • Check the ground path and continuity from the LDP connector to chassis/PCM ground.
  • Look for a short to battery voltage on the LDP circuit when it should be off (if the PCM reports the circuit high while off, this points to a wiring fault or a stuck/failed actuator).
• If you have access to a waveform or scanner data that shows LDP drive/duty cycle, observe whether the LDP is being commanded correctly and whether the voltage level corresponds to a normal on/off state.

4) Read/interpret live data and readiness status

• Use a capable scan tool to view EVAP-related live data, including LDP voltage, current draw (if available), and duty cycle, as well as related purge/solenoid status.
• If the LDP voltage remains abnormally high or if commanded low voltage is not achieved, focus on the electrical path: wiring harness, connectors, grounds, and the LDP control circuit in the PCM.

5) Electrical fault isolation

• If possible, isolate the LDP circuit from the PCM by verifying the circuit through the harness with a known-good connector/short test (only if service data and safe test procedures permit). Look for:
  • Open circuit in the LDP feed or ground.
  • Short to power or to ground in the LDP circuit.
  • A damaged or corroded harness connector that prevents proper signal return.

6) Mechanical/evap system checks (to rule out interactions)

• Confirm there are no obvious vacuum leaks that would distort EVAP tests, but remember P2402 specifically points to the electrical circuit; a leak could still coexist with an electrical fault.
• If the LDP tests or pump function appear physically abnormal (noisy operation, intermittent operation), prepare to service/replace the LDP per manufacturer guidance.

7) Repair/replace, followed by validation

• If the LDP or its driver is confirmed faulty (stuck energized, short to power, internal failure), replace the LDP. If the wiring/connectors are at fault, repair or replace damaged wiring and secure connectors.
• If the PCM input/output or control circuit is suspected (software fault or internal PCM issue) consult manufacturer service information for possible reflash/TSB or replacement if indicated.
• After repair, perform an EVAP system test or drive cycle recommended by the vehicle's service data to re-run EVAP tests. Clear the P2402 code and verify that the code does not return.

8) Post-repair verification

• Clear codes and perform a complete drive cycle to re-establish readiness monitors, including EVAP tests per the vehicle's procedure.
• Confirm that P2402 does not reoccur and that any related EVAP codes (if present) resolve or reduce in severity.
• If the code reappears, re-evaluate the electrical path and consider an alternate cause (PCM fault, additional wiring faults, or a secondary component in the EVAP path).

Notes on safety and procedure

• EVAP systems deal with fuel vapors that are hazardous; work in a well-ventilated area and avoid ignition sources.

• When working on electrical circuits, disconnect the battery if required by the vehicle's service procedure, and follow proper lockout/tagout practices.

• Use the vehicle's service information for exact LDP location, wiring diagram, connector pinouts, expected voltages, and any manufacturer-specific test steps.

• If unsure, consult manufacturer service bulletins (TSBs) for known P2402-related issues for the specific make/model.

• Diagnostic Trouble Codes and their role in OBD-II - emphasizes trunk concept: codes signal monitored parameter faults within powertrain/emissions systems.

• Powertrain Codes - confirms P-codes categorization and emphasis on emission-related powertrain diagnostics.

• Emissions Testing - EVAP-related errors impact emissions readiness and testing outcomes, underscoring the importance of diagnosing EVAP faults properly.

• Open Source code definitions - provides the direct mapping for P2402 as EVAP Leak Detection Pump Circuit High.

Practical Tips

• Note the exact code (P2402) and its interpreted meaning (EVAP Leak Detection Pump Circuit High).
• Record observed symptoms (MIL on, any drivability concerns, emissions-test impact) and data from freeze-frame/live data (LDP voltage, circuit state).
• List inspected components (LDP, harness, connectors, grounds) and the results of electrical checks.
• Document any repairs performed (LDP replacement, wiring repair, connector replacement, PCM service) and the post-repair validation steps (drive cycle, EVAP tests, code clear and re-check).

This diagnostic guide was generated using verified reference data:

• Wikipedia Technical Articles: OBD-II
• Open-Source OBD2 Data: N/A (MIT)

Content synthesized from these sources to provide accurate, real-world diagnostic guidance.

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