P2420
EVAP System Switching Valve Control Circuit High
Evaporative emissions (EVAP)
Generic OBD-II
Low
What it means
P2420 means the ECM sees high voltage on the control circuit for the EVAP switching valve — usually an open circuit, a short to power, a bad connector, or a failed solenoid. This is an electrical fault in the fuel-vapor system, not a leak, so the car drives normally. It mainly stops the EVAP monitor from completing until it's fixed.
Low
Can I keep driving? Yes — no effect on driving; it's an emissions-control circuit fault to fix before an emissions test.
Common symptoms
What you'll notice
- Check-engine light on
- No change in how the car drives
- May fail an emissions/readiness check
Common causes
Most likely first
- Open circuit (reads high voltage) in the EVAP switching-valve control wireLikely
- Faulty EVAP switching valve solenoidCommon
- Corroded or loose connector at the valveCommon
- Short to power in the control circuitLess often
- ECM driver fault (less common)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data to see when the fault set.
- Check the switching-valve connector and control wiring for an open or short to power.
- Test the solenoid's resistance against spec.
- Verify the ECM's control-driver operation.
- Replace the switching valve if faulty, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with P2420?+
Yes — it's an emissions-control circuit fault with no drivability impact. Repair it before an emissions test so the EVAP monitor can complete.
Can I just clear P2420?+
It returns until the open/short in the control circuit or the faulty valve is repaired.
Related codes
Often seen with P2420
Read & clear P2420 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX