obd2.help

P3400

Cylinder Deactivation System Bank 1

Your engine is having a problem with the system that turns some cylinders off during light driving. The computer has detected a fault on bank 1 and stores code P3400. This can cause poor fuel economy, rough running, or a check engine light.

Severity3/5 Moderate
Can I drive?⚠ With caution

The vehicle is usually drivable, but the engine may run rough or use more fuel. If the engine misfires badly, loses power, or makes unusual noises, stop driving and diagnose it soon.

DIY
$20–$250
Shop
$150–$800
Difficulty
intermediate

What It Means

P3400 sets when the powertrain control module detects a malfunction in the cylinder deactivation system for bank 1. Depending on the engine, this may involve valve lifters, oil control solenoids, wiring, oil pressure, or the control module failing to command cylinder shutdown correctly. The fault may be electrical, mechanical, or related to engine oil condition or pressure.

Symptoms

Common Causes

1. Low engine oil level, dirty oil, or wrong oil viscosity affecting hydraulic cylinder deactivation partshigh
2. Failed or sticking cylinder deactivation solenoid, lifter, or oil control valve on bank 1high
3. Wiring problem, loose connector, or corrosion in the cylinder deactivation circuitmedium
4. Oil pressure problem from worn engine, clogged pickup, or failing oil pumpmedium
5. Engine control module software issue or internal module faultlow
6. Mechanical engine wear or valve train damage affecting cylinder deactivation operationlow

Related Codes

FAQ

Is P3400 serious?

It is usually a moderate issue, but it can become serious if it is caused by low oil pressure or internal engine damage.

What does bank 1 mean?

Bank 1 is the side of the engine that contains cylinder number 1.

Can low oil cause P3400?

Yes. Low oil level, dirty oil, or the wrong oil can prevent the cylinder deactivation system from working correctly.

Will an oil change fix P3400?

Sometimes it will, if the oil is low, dirty, or the wrong type. If the fault remains, more diagnosis is needed.