What Does P3408 Mean?
The PCM has detected an abnormally high voltage in the cylinder 1 exhaust valve control circuit. This suggests an open circuit condition, short to power, or loss of ground connection.
Common Causes
35%
Open circuit in ground connection for exhaust valve solenoid
25%
Wiring harness shorted to voltage source (power)
20%
Failed exhaust valve control solenoid with internal open
15%
Corroded or loose connector causing high resistance
5%
PCM driver circuit failure stuck high
Diagnostic Steps
1
Step 1: Check and clean all ground connections for valve control solenoid circuit, including engine grounds
2
Step 2: Measure voltage at solenoid connector with key on; should see battery voltage only when PCM commands solenoid on
3
Step 3: Check for short to power by measuring voltage on control wire with solenoid disconnected and key on
4
Step 4: Test solenoid resistance and verify it matches specifications; replace if open circuit detected
5
Step 5: Verify PCM can pull control circuit low by commanding solenoid on with scan tool while monitoring voltage
Estimated Repair Cost
$150 - $850
Parts + labor, varies by vehicle and location
The PCM has detected an abnormally high voltage in the cylinder 1 exhaust valve control circuit. This suggests an open circuit condition, short to power, or loss of ground connection.
The most common cause of P3408 (Cylinder 1 Exhaust Valve Control Circuit High) is: Open circuit in ground connection for exhaust valve solenoid
Typical repair costs for P3408 range from $150 to $850, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle remains drivable but will have reduced performance and fuel economy. No immediate safety risk but should be repaired to prevent potential catalytic converter damage.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P3408 to identify the root cause.
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Quick Info
Category
Powertrain
System
Variable Valve Timing/Lift System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
