The engine control module has detected a fault in the cylinder deactivation system on bank 1. Variable displacement engines shut off cylinders under low load to save fuel — a fault here disables the function.
Medium severity. Can I keep driving?Drive little and gently. If you hear timing chain noise or the oil light comes on, shut off the engine.
Bank 1 is the side of the engine with cylinder 1. Inline engines only have this bank.
Most likely causes
- Deactivation solenoid or oil control valve failed
- Collapsing lifter stuck
- Low oil pressure prevents activation
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: hard
- It affects emissions.
What each character of P3400 means
- P: Powertrain: engine and transmission
- 3: Generic or manufacturer code, depending on the range
- 4: Emissions
- 00: Specific fault in that system
Frequently asked questions
Can I keep driving with code P3400?
Drive little and gently. If you hear timing chain noise or the oil light comes on, shut off the engine.
What causes code P3400?
The most common causes are: deactivation solenoid or oil control valve failed; collapsing lifter stuck; low oil pressure prevents activation.
Related codes
- P3410Cylinder 2 Deactivation/Intake Valve Control Performance
- P3497Cylinder Deactivation System Bank 2
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.