What Does P2420 Mean?
The PCM detects that the EVAP switching valve control circuit voltage is higher than expected. The circuit has an open or is shorted to voltage.
Common Causes
35%
Control wire shorted to battery voltage in harness
25%
Failed EVAP switching valve with internal short to power
20%
Damaged connector pins causing short to adjacent power wire
15%
Aftermarket wiring or accessory installation causing cross-connection
5%
PCM driver circuit stuck high
Diagnostic Steps
1
Step 1: Disconnect EVAP switching valve connector and measure voltage on control wire from PCM - should be 0V with key on
2
Step 2: If voltage present with valve disconnected, trace wiring for short to power source
3
Step 3: Inspect connector terminals for bent pins contacting adjacent circuits
4
Step 4: Check for recent electrical work or accessory installations that may have damaged harness
5
Step 5: If no wiring faults found, test valve resistance and replace if out of specification
Estimated Repair Cost
$150 - $550
Parts + labor, varies by vehicle and location
The PCM detects that the EVAP switching valve control circuit voltage is higher than expected. The circuit has an open or is shorted to voltage.
The most common cause of P2420 (Evaporative Emission System Switching Valve Control Circuit High) is: Control wire shorted to battery voltage in harness
Typical repair costs for P2420 range from $150 to $550, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. Will not pass emissions inspection and may experience fuel odor if purge system affected.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2420 to identify the root cause.
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Quick Info
Category
Powertrain
System
Evaporative Emissions System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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