P2418

Code

Generic P — Powertrain

EVAP System Switching Valve Control Circuit/Open

Brand: Generic

Type: P — Powertrain

Views: UK: 30 EN: 75 RU: 44

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Page language: EN

Causes

Broken or disconnected wiring to the EVAP switching/vent valve
Corroded, loose or damaged connector or pins at the valve
Failed EVAP switching/vent valve (open coil or internal break)
Blown fuse, bad relay or loss of power/ground to the valve circuit
Poor ECM/PCM driver output (internal transistor failure)
Water intrusion or physical damage to harness near valve

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Stored P2418 and possibly other EVAP-related codes
Failed emissions test or readiness monitor incomplete
Possible fuel odor under certain conditions (if venting abnormal)
Occasional rough idle or drivability issues if EVAP flow uncontrolled (less common)

What to check

Read freeze frame and pending codes with a scan tool; note related EVAP codes
Visual inspection of wiring and connectors at the EVAP switching/vent valve and along harness
Check for corrosion, pin damage, water intrusion or rodent damage
Verify fuse(s) and any related relays for the EVAP/PCM circuits
Measure continuity and resistance of the valve coil with harness disconnected
Back-probe the valve connector and observe voltage/ground while commanding the valve with a scanner

Signal parameters

Typical solenoid coil resistance (cold): roughly 20–80 ohms (varies by vehicle); an open is infinite/OL
Resting voltage at valve supply terminal: battery voltage (~11–14 V) with key ON
When commanded ON: PCM switches ground (or supply) — back-probed voltage may show pulsed or switched ground; expected change from supply to near 0 V when driven
PCM drive may use PWM; frequency commonly 20–200 Hz depending on design
No continuity or infinite resistance on coil indicates open circuit

Diagnostic algorithm

Verify the code and note any related EVAP codes using an OBD-II scan tool. Clear codes and attempt to re-run to confirm repeatability.
Perform a thorough visual inspection of the EVAP switching/vent valve, harness, and connectors. Repair any obvious damage or corrosion.
Locate applicable fuse(s) and relays for the EVAP/PCM circuits and verify supply voltage with key ON.
Disconnect the valve connector and measure coil resistance. If resistance is open/infinite, replace the valve.
With harness connected, back-probe the valve connector. With key ON, verify constant supply voltage at the power terminal. Command the valve ON with a scan tool and observe the driver terminal for expected switching to ground or supply.
If supply and command signals are correct but valve does not operate and coil resistance is good, check for restricted vacuum lines or mechanical binding; replace valve if necessary.
If command signal is absent or driver does not switch, trace wiring for continuity between valve connector and PCM ground/supply. Repair any open or shorted wiring.
If wiring checks good and the PCM does not drive the circuit when commanded, perform PCM output tests per manufacturer service information; consider PCM replacement only after all wiring and component tests confirm a good circuit.
After repairs, clear codes, perform functional tests with a scan tool, and complete drive cycle or smoke test to verify EVAP system operation and ensure no new codes set.

Likely causes

Open circuit in the valve control wire (broken conductor)
Corroded connector causing loss of electrical continuity
Valve coil has gone open (electrical failure)
Blown fuse or missing battery feed to the circuit
Faulty ECM output stage (less common)

Fault status

⚠️ Status

P2418: ECM detected an open or interrupted electrical circuit for the EVAP system switching/vent valve while commanding the valve, indicating the controller cannot confirm the valve's expected electrical response.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.5 hours