P2420

Code

LAND ROVER P — Powertrain

Evaporative Emission Control System Switching Valve control - high circuit

Brand: LAND ROVER

Type: P — Powertrain

Views: UK: 16 EN: 40 RU: 20

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Page language: EN

Causes

Open or damaged wiring in the switching valve control circuit
Short to battery voltage on the control circuit
Corroded or poorly connected valve connector or pins
Failed switching/vent solenoid (internal open or shorted coil)
Faulty ECM driver output
Aftermarket modifications or repairs that disturbed the harness

Symptoms

Check Engine Light (MIL) illuminated
Possible EVAP system warning/message (may reduce emissions performance)
Failed emissions test or drivability-related limp-home modes in some vehicles
Noisy or non‑operational vent/switching valve (may be intermittent)
Poor purge control or EVAP system unable to complete self-tests

What to check

Read freeze frame and live data for EVAP switching valve status and related EVAP codes
Visually inspect the switching valve, connector, and wiring for damage, corrosion, or disconnection
Backprobe the control connector and monitor voltage while commanding the valve ON/OFF with a scan tool
Measure coil resistance at the valve with the connector disconnected (compare to specification)
Check for short to battery (voltage present when driver should pull circuit low) and short to ground
Inspect fuses and engine/chassis grounds related to the EVAP circuit

Signal parameters

Typical coil resistance (valve): ~15–40 ohms (vehicle-specific; check OEM spec)
Expected control signal when ECM commands valve ON: driver grounds the circuit -> near 0 V at valve control pin
Expected control signal when ECM commands valve OFF: ECM releases driver -> close to vehicle battery voltage or open-circuit (approx. 12V)
High-circuit fault: control voltage is higher than expected for commanded state or above ECM input threshold
Monitor current draw when energized: normal small coil current (tens to hundreds of mA); abnormally low or zero current suggests open coil

Diagnostic algorithm

Retrieve and record DTCs and freeze frame data. Note related EVAP codes (P0440–P0457 range).
Visually inspect switching valve, vacuum hoses, and harness for damage, contamination, or pin corrosion.
With ignition ON (engine off), backprobe the valve connector and command the valve ON/OFF using a scan tool while observing voltage: verify ECU grounds circuit to energize valve (voltage should drop toward 0 V when commanded ON).
If voltage does not behave as expected, disconnect the connector and measure for B+ on the control wire (presence of battery voltage when driver should ground implies short to B+).
Measure solenoid coil resistance at the valve with connector disconnected. If out of spec (open or very high), replace valve.
Perform a wiggle test on harness while monitoring live signal to reproduce intermittent faults.
If wiring appears open or shorted, perform continuity tests to the ECM pin and check for short to battery or ground. Repair wiring as needed.
If wiring and valve check good, verify ECM driver output at the ECM connector. If ECM driver is faulty, consider ECM repair/replacement per OEM procedures.
After repair, clear codes, complete EVAP system readiness/self-tests, and road test. Re-scan to confirm no return of P2420.

Likely causes

Disconnected or corroded connector at the switching valve
Broken conductor or chafed wiring rubbing to chassis (open/short)
Solenoid coil open or internally high resistance
Short to B+ on the control wire (voltage present when it should be low)
ECM driver damaged (less likely than wiring/valve)

Fault status

⚠️ Status

Evaporative Emission Control System switching/vent valve control circuit reports a high voltage condition. The ECM detects voltage outside the expected range on the valve control circuit indicating an electrical fault.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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P2420 — Evaporative Emission Control System Switching Valve control - high circuit