What Does P3420 Mean?
The PCM detected a higher than expected voltage in the cylinder 3 intake valve deactivation control circuit. This indicates a potential short to voltage, open circuit, or failed solenoid.
Common Causes
30%
Open circuit in wiring harness to cylinder 3 intake valve control solenoid
30%
Failed cylinder 3 intake valve control solenoid (internal open circuit)
20%
Short to voltage in solenoid control circuit
15%
Damaged or disconnected electrical connector at solenoid
5%
PCM internal driver circuit failure
Diagnostic Steps
1
Step 1: Inspect cylinder 3 intake valve control solenoid connector for proper connection and terminal damage
2
Step 2: Disconnect solenoid and measure resistance; infinite resistance indicates open solenoid
3
Step 3: Check for voltage at solenoid connector with key on, engine off (should be zero volts)
4
Step 4: Test continuity of control circuit from PCM to solenoid connector for opens
5
Step 5: Check for short to battery voltage using test light or multimeter on control wire
Estimated Repair Cost
$150 - $650
Parts + labor, varies by vehicle and location
The PCM detected a higher than expected voltage in the cylinder 3 intake valve deactivation control circuit. This indicates a potential short to voltage, open circuit, or failed solenoid.
The most common cause of P3420 (Cylinder 3 Deactivation/Intake Valve Control Circuit High) is: Open circuit in wiring harness to cylinder 3 intake valve control solenoid
Typical repair costs for P3420 range from $150 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is safe to drive but fuel economy will be reduced. Engine may run roughly during deactivation mode transitions.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P3420 to identify the root cause.
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Quick Info
Category
Powertrain
System
Variable Valve Timing/Cylinder Deactivation System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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