P3400: Cylinder Deactivation System Bank 1
3 vehicles · 3 makes · $400-$4,500 repair
Most Reported On
P3400 is an OBD-II diagnostic trouble code meaning “Cylinder Deactivation System Bank 1.” This code indicates the engine control module detected a fault in the cylinder deactivation (variable displacement) system on bank 1, the side of the engine containing cylinder number one. Cylinder deactivation closes the valves and cuts fuel to certain cylinders under light load to save fuel, using oil-pressure-operated control solenoids. When the system can't operate correctly, the module sets this code; you may notice reduced fuel economy, a slight performance change, or a warning light. The most common trigger is low oil level or poor oil pressure. This code is most commonly reported on 2010-2013 Acura MDX, 2010-2015 Chevrolet Camaro (SS), and 2023-2025 Mazda CX-50, with repair costs ranging from $400 to $4,500.
Common Causes
Typical Repair Cost
Based on 3 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose P3400, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
- Read & clear engine codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X OBD-II Scanner
by LAUNCH
A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
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Vehicles Affected (3)
FAQ
What does P3400 mean?
P3400 stands for "Cylinder Deactivation System Bank 1." This code indicates the engine control module detected a fault in the cylinder deactivation (variable displacement) system on bank 1, the side of the engine containing cylinder number one. Cylinder deactivation closes the valves and cuts fuel to certain cylinders under light load to save fuel, using oil-pressure-operated control solenoids. When the system can't operate correctly, the module sets this code; you may notice reduced fuel economy, a slight performance change, or a warning light. The most common trigger is low oil level or poor oil pressure.
What are the most common causes of P3400?
The most common causes of P3400 are: Low engine oil level or low oil pressure, Clogged or dirty oil passages/lifters, Faulty active fuel management / cylinder deactivation solenoid, Failed deactivating lifter or collapsed lifter, Wiring or connector fault in the solenoid circuit, Sludge from missed oil changes, Faulty oil pressure sensor. The specific cause varies by vehicle.
How much does it cost to fix P3400?
Repair costs for P3400 range from $400 to $4,500, depending on the vehicle and root cause.
Which vehicles are affected by P3400?
Au7o has documented P3400 across 3 vehicle models from 3 manufacturers: Acura, Chevrolet, Mazda.
Sources (6)
- articleVariable Cylinder Management Fix (Transmission Digest)
- ForumDisable VCM (MDXers.org)
- ForumBROKEN ENGINE MOUNTS: Send me your information!
- TSBGM Special Coverage 14311 / AFM Valve Lifter Failure on certain GM vehicles with LC9/LMG/LH6/L94/L99
- ForumCamaro5 forum discussions documenting L99 AFM lifter collapse and cam damage
- ForumCarComplaints: 2025 Mazda CX-50 Cylinder Deactivation Solenoid (P3400 + metal shavings)
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.