P3497: Cylinder Deactivation System Bank 2
What to do
Check the engine oil level and condition before anything else — these systems are actuated by oil pressure, and low or degraded oil is a leading cause rather than a preliminary check. The car will usually drive normally with the deactivation system switched off, which mostly costs fuel economy. If it is also misfiring, ticking, or running rough, stop driving it: a deactivating lifter that has failed mechanically can wear the camshaft, turning a solenoid job into an engine rebuild.
What this code means
The cylinder deactivation system on bank 2 has reported a fault at system level.
This is the summary code, and on its own it is the useful one.
With per-cylinder codes beside it, this is the consequence — the module has concluded the system is not fit to use and has switched it off. Standing alone, every individual circuit tested healthy and the system still did not do its job, which points away from solenoids and wiring and toward what they all depend on: oil pressure, oil condition, and the module's own decision to disable.
Many vehicles disable deactivation for entirely normal reasons, and a stored code is not always one of them. It stays off when the oil is cold, when the engine is under load, when the battery is low, and on some vehicles when the oil is overdue by the maintenance monitor. A system that never engages is not necessarily faulty; it may be being told not to.
Cylinder deactivation shuts down half the engine while you are driving, and the driver is not meant to notice.
Under light load — a level motorway cruise asks a large engine for a small fraction of what it can make — an engine wastes fuel pumping air it does not need. The throttle is nearly closed, so every intake stroke drags against a vacuum. That pumping loss is a real fraction of the fuel burned.
So the engine switches cylinders off: fuel and spark stop, and the valves are held shut. The remaining cylinders must then work harder to make the same power, which opens the throttle further and reduces the pumping loss for all of them. That is the whole gain — it comes from unthrottling the cylinders still running, not from the ones that stopped.
Almost all of these systems are actuated by engine oil, and that is why oil condition dominates the causes.
The solenoid does not move the valve. It routes oil pressure to a lifter that collapses, so the camshaft lobe pushes into a part that gives way instead of opening the valve. The oil is the working fluid, the signal path and the lubricant at once.
Which makes this system unusually sensitive to oil that a normal engine would tolerate. Oil that is old, overdue, of the wrong viscosity, or diluted with fuel is slower to move and more likely to leave varnish in passages narrower than a pencil lead. Low oil level does it too, because the pressure that holds a lifter in position falls away first at idle when it is hot.
So before condemning a solenoid: check the oil level, the oil condition and when it was last changed. On these engines that is diagnosis, not a preliminary.
The honest summary of what this costs you. With deactivation disabled the engine runs on all its cylinders all the time. It will drive normally and use a few per cent more fuel — which is why this code is easy to ignore, and why it is worth reading the oil-level advice above rather than ignoring it.
Likely causes
Start here
- Low or dirty engine oil · easy
- Genuinely low oil pressure · specialist
Less common
- Blocked deactivation solenoid oil screen · specialist
Rare
- Faulty engine control module · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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