OBD-II Diagnostic Trouble Code
P2420 — EVAP Vent Solenoid Control Circuit/Open
The ECM detected an open circuit or an electrical fault in the control circuit of the EVAP canister vent solenoid. The vent solenoid opens and closes the canister to fresh air, and it must close for the EVAP leak test. With the circuit open, the ECM cannot command the valve, which on most systems leaves it in its normally open position. This applies to gasoline trucks.
Severity 2/5
Less common on commercial trucks
Service soon
Severity
Service soon
EVAP Vent Solenoid Control Circuit/Open
Code
P2420
Category
Powertrain
Subsystem
Emissions
Truck-relevant
Less common
What this means for truckers
P2420 (EVAP Vent Solenoid Control Open) — gas engine.
Before you replace parts — try this first
P2420 on the Emissions system is most often broken or corroded wiring or connector at the vent solenoid, which sits near the tank and is exposed to road spray — not a dead part. On commercial diesels especially, work these in order before spending money on parts:
- Confirm the symptoms. Match what your truck is doing to the Symptoms section below. If the code is set but the symptoms are not there, clear the code and re-test after a drive cycle — it may not return.
- Clean and dry the sensor connector. Water, road salt, or oil seeping into a connector is the #1 fake sensor failure. Disconnect, look for green corrosion or moisture, spray with electrical contact cleaner, dry, reseat. Many faults clear here for $0.
- Inspect the wiring harness. Trace the wire from the sensor toward the ECM — look for chafing against the engine block, melted insulation near the turbo or exhaust, or pinch points where a clamp has rubbed through.
- Test the sensor before swapping it. Most Common Causes (below) list the expected voltage or resistance range — a $20 multimeter saves a $300 sensor swap that does not fix the problem.
- Only then, replace the part. Use the OEM or a tier-1 aftermarket. Cheap sensors throw the same code in two weeks.
Symptoms
The check-engine light comes on and the EVAP monitor will not run or complete. Because the valve usually stays in its normally open position, refueling and engine performance are normally unaffected. The truck may fail an emissions readiness check.
Common causes
- CommonBroken or corroded wiring or connector at the vent solenoid, which sits near the tank and is exposed to road spray ($80–$300)
- CommonVent solenoid coil open internally ($120–$350)
- OccasionalBlown fuse or loss of power feed to the solenoid ($20–$120)
- RareECM driver failure ($800–$2000)
How to fix
Check the EVAP or emissions fuse and confirm battery voltage on the solenoid feed with the key on
When to use: First step
Measure the solenoid coil resistance and compare it to spec
When to use: To decide whether the solenoid or the wiring is at fault
Check the control wire for continuity from the solenoid to the ECM and repair any corroded or broken sections
When to use: When the coil tests good
Replace the vent solenoid and clear the code
When to use: When the coil is open or shorted
Affects most
No specific vehicle pattern found in our complaint database. This code can appear on any vehicle that supports OBD-II diagnostics.
Related
- → Browse all DTC trouble codes
- → Decode a VIN to check codes for your truck
- → Owner-operator maintenance guides
- → P244A — Diesel Particulate Filter Differential Pressure Too Low
- → P244B — Diesel Particulate Filter Differential Pressure Too High
- → P244C — Exhaust Gas Temperature Too Low Bank 1
- → P244D — Exhaust Gas Temperature Too High Bank 1
- → P245A — EGR Cooler Bypass Control Circuit/Open
Frequently Asked Questions
Can I drive with code P2420?
P2420 is severity 2 — service this week. Not an immediate stop, but ignoring it usually compounds the problem. Most common cause for this code is a worn sensor or minor performance fault that won't strand you today but will get more expensive the longer you wait.
How much does it cost to fix P2420 on a commercial truck?
Total repair cost ranges $20–$2000 depending on the root cause. The cheapest fix is usually the first one listed below — Broken or corroded wiring or connector at the vent solenoid, which sits near the tank and is exposed to road spray — which is also the most common. On commercial trucks the cost is usually higher than passenger vehicles due to part availability and shop labor rates ($120–185/hour at most truck shops, vs $90–130 at general auto shops). DIY-capable fixes (sensors, hoses, filters) are at the low end; major component replacements (turbo actuator, high-pressure fuel pump, transmission solenoid pack) are at the high end. Always diagnose with a scan tool BEFORE replacing parts — guessing wrong on a $1,500 turbo actuator when the actual issue was a $30 boost hose is a common expensive mistake.
Will P2420 fail a DOT inspection?
Yes — P2420 is an emissions-related code, and DOT inspectors check emissions compliance. An active emissions code with a check engine light can result in an out-of-service violation under FMCSA Part 393. The truck typically can't be moved until the code is cleared. Repeated emissions violations escalate to CSA scores.
What's the difference between P2420 and related codes?
P2420 is closely related to: P244A (Diesel Particulate Filter Differential Pressure Too Low), P244B (Diesel Particulate Filter Differential Pressure Too High), P244C (Exhaust Gas Temperature Too Low Bank 1), P244D (Exhaust Gas Temperature Too High Bank 1). These codes share the same subsystem (emissions) and often appear together. If you see this code, scan for the full code list — fixing the root cause usually clears multiple companion codes at once. If only P2420 is set without the companions, the issue is more isolated.
How do I prevent P2420 from coming back after a repair?
For P2420 (EVAP Vent Solenoid Control Circuit/Open), prevention centers on the emissions system. Keep up with PM on the EGR system — clean the valve at 200K miles. Use OEM-spec air filters. Don't ignore minor codes; they often escalate into bigger emissions failures.