What Does P3400 Mean?
The cylinder deactivation system on Bank 1 has detected a malfunction. This system shuts off cylinders during light load conditions to improve fuel economy.
Common Causes
35%
Failed cylinder deactivation solenoid
30%
Low or contaminated engine oil affecting hydraulic operation
20%
Stuck or worn valve lifters
15%
Wiring harness or connector issues
Diagnostic Steps
1
Step 1: Check engine oil level and condition; verify proper viscosity and change if contaminated
2
Step 2: Monitor cylinder deactivation solenoid operation using scan tool data parameters
3
Step 3: Test deactivation solenoid electrical circuits for proper voltage and resistance
4
Step 4: Perform mechanical inspection of valve lifters and deactivation components if electrical tests pass
Estimated Repair Cost
$250 - $1,800
Parts + labor, varies by vehicle and location
The cylinder deactivation system on Bank 1 has detected a malfunction. This system shuts off cylinders during light load conditions to improve fuel economy.
The most common cause of P3400 (Cylinder Deactivation System Bank 1) is: Failed cylinder deactivation solenoid
Typical repair costs for P3400 range from $250 to $1,800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is safe to drive but may experience reduced fuel economy and slight roughness. Engine may run on all cylinders continuously.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P3400 to identify the root cause.
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Quick Info
Category
Powertrain
System
Cylinder Deactivation System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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