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Home / DTC / P2451 — Evaporative emission control system switching valve press

P2451 — Evaporative emission control system switching valve press

Detailed page for trouble code P2451.

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Code

P2451

LAND ROVER P — Powertrain

Evaporative emission control system switching valve press

Brand: LAND ROVER
Type: P — Powertrain
Views: UK: 4 EN: 39 RU: 6
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Page language: EN

Causes

  • Failed EVAP switching/purge valve (stuck, clogged or internally shorted)
  • Open or shorted wiring to the valve (connector corrosion, damaged insulation, pin pushed out)
  • Poor electrical ground or low supply voltage to the valve
  • Blocked or collapsed EVAP hoses or ports restricting flow
  • Faulty fuel tank pressure/EVAP sensor providing incorrect pressure feedback
  • Leaking charcoal canister or internal canister restriction

Symptoms

  • Malfunction Indicator Lamp (MIL) / Check Engine Light illuminated
  • Failed or intermittent EVAP system readiness, possible failed emissions test
  • Fuel odor near the fuel tank or EVAP canister area
  • Possible rough idle or reduced fuel economy if purge stuck open
  • No noticeable drivability symptoms in some cases

What to check

  • Retrieve freeze frame and live data with a capable scan tool; note EVAP switching valve commanded vs actual state and pressure-related PIDs
  • Perform a visual inspection of the valve, connector, and wiring for damage, corrosion or loose pins
  • Measure valve coil resistance with an ohmmeter and compare to specs
  • Backprobe connector to verify supply voltage (battery) and control signal from PCM while commanding the valve
  • Listen for valve actuation (click) while commanding ON/OFF with a scan tool
  • Perform a smoke/leak test on the EVAP plumbing to check for restrictions or leaks

Signal parameters

  • Supply voltage to valve: ~12 V (battery voltage) with ignition ON
  • Control signal: switched ground or PWM from PCM (0–12 V range depending on design)
  • Coil resistance: typically tens to hundreds of ohms (refer to service manual)
  • Current draw: valve-specific (tens to a few hundred mA while energized)
  • Commanded state vs reported state: ON/OFF or duty cycle percentage
  • Fuel tank / EVAP pressure reading: kPa or bar values reported by pressure sensor

Diagnostic algorithm

  1. Verify the code is current: clear DTCs and perform a drive cycle to see if P2451 returns.
  2. Inspect wiring and connectors at the EVAP switching valve and associated harness for corrosion, looseness, or damage.
  3. With ignition ON, measure supply voltage at the valve connector; confirm good battery voltage and solid ground reference.
  4. Command the valve ON/OFF with a scan tool while monitoring voltage and current; listen for a click and note any lack of response or slow reaction.
  5. Measure coil resistance on the valve; compare to vehicle-specific specification. Replace valve if open or shorted.
  6. Perform an EVAP smoke test to identify clogged passages, leaks, or a stuck valve that prevents proper pressurization or venting.
  7. Isolate and bench-test the valve: apply battery voltage to the appropriate pins to verify actuation and flow. Do not apply excessive voltage.
  8. Check the fuel tank pressure/EVAP sensor readings while commanding the valve to confirm the PCM is receiving expected pressure changes.
  9. Repair or replace damaged wiring, connectors, hoses, valve or pressure sensor as indicated by test results.
  10. After repairs, clear codes and verify repair with a complete EVAP system readiness drive cycle.

Likely causes

  • Corroded connector or broken wire to the EVAP switching valve
  • Valve coil resistance out of specification (shorted or open)
  • Vacuum/vent hose disconnected or pinched at the valve port
  • Clogged charcoal canister or valve port preventing pressure change
  • Intermittent ground causing erratic valve operation

Fault status

⚠️ Status
Evaporative Emission Control System — Switching/evap purge valve pressure or control circuit fault detected. Valve not responding or pressure feedback out of expected range.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

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