P3400 fault code: what it means

P3400: Variable Cylinder Management (VCM) cylinder deactivation fault, bank 1 (rear bank) on Honda J35 V6 (Odyssey, Pilot, Accord V6). The oil-pressure operated rocker system is not switching properly.

Engine and gearbox (powertrain) · Costly if missed

Usual causes, most likely first

1. low engine oil level
2. bank 1 rocker arm oil pressure switch
3. faulty VCM oil control solenoid
4. dirty or wrong grade oil

P3400 by make

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Before you clear it

Write the code down or photograph the scanner first. A code that comes straight back after clearing points to a fault that is still there. A car whose codes were cleared just before you arrived may be hiding one: the scanner's readiness monitors show "not ready" for a while after codes are cleared.

Researched by Credov from manufacturer and workshop sources. A fault code points to where a fault may be; a workshop confirms it with a diagnosis. Browse all fault codes.