P3400 Cylinder Deactivation System (Bank 1)
P3400 is a generic OBD2 powertrain code. It means “Cylinder Deactivation System (Bank 1)” — the same on every make and model, because the definition comes from the SAE J2012 standard rather than from the carmaker.
Ask the AI about P3400 on your car- System
- Powertrain (P)
- Code type
- Generic (SAE)
- Range
- P34xx
What the wording tells you
Bank 1: engines with two rows of cylinders — V6, V8, boxer — have two banks. Bank 1 is the side that holds cylinder 1, bank 2 the other side; an inline engine has only bank 1.
Can I keep driving with P3400?
The rule of thumb for this area (cylinder deactivation & valve control): Usually drivable — the engine keeps every cylinder running — but check the oil level first, and don’t ignore a ticking noise: a stuck lifter can damage the camshaft.
How P3400 breaks down
Powertrain. Engine, transmission, fuel and emissions — the codes behind the check engine lamp.
Generic code: defined by SAE, the same on every make.
Cylinder deactivation & valve control.
The specific fault within this range.
Where to look: Cylinder deactivation & valve control
Engines that shut off cylinders at light load to save fuel — and some variable-valve-lift systems — use oil-pressure-controlled lifters or valve actuators on each cylinder. These codes cover their control circuits and performance.
Typical causes in this area
- Low, old or wrong-grade engine oil
- Failed deactivation solenoids
- Collapsed or sticking lifters
- Wiring to the valve-control solenoids
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Read and clear P3400 on your iPhone
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Frequently asked
What does P3400 mean?
P3400 is a generic OBD2 powertrain code. It means “Cylinder Deactivation System (Bank 1)” — the same on every make and model, because the definition comes from the SAE J2012 standard rather than from the carmaker.
Can I drive with P3400?
The rule of thumb for this area (cylinder deactivation & valve control): Usually drivable — the engine keeps every cylinder running — but check the oil level first, and don’t ignore a ticking noise: a stuck lifter can damage the camshaft.
What causes P3400?
Typical causes in this area: Low, old or wrong-grade engine oil; Failed deactivation solenoids; Collapsed or sticking lifters; Wiring to the valve-control solenoids.
How do I clear P3400?
Fix the cause first, then clear it with any OBD2 scanner or app. Once the fault is gone the car also clears it on its own: the check engine lamp goes off after the self-test passes on three drive cycles in a row, and the stored code ages out after about 40 warm-ups. Clearing without a repair only hides it for a while — and resets the readiness monitors an emissions inspection looks at.
Is P3400 the same on every car?
Yes. P3400 is a generic SAE J2012 code, so its definition is identical on every make and model. What differs is the cause behind it and the repair procedure, which depend on the engine — that’s why the assistant on this page asks for your car.
Guides
Definitions: the generic SAE J2012 codes from Brimly’s offline dictionary (data version 2026.09). Causes and advice are general guidance for all makes — the service information for your car has the last word.