P3400Cylinder Deactivation System Bank 1
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P3400 is the bank-level verdict: the engine computer has concluded that cylinder deactivation on bank 1 as a whole does not behave as commanded, without blaming a single circuit. Makers fill it differently. On the 2019 LT4 Corvette, GM compares a manifold pressure model with all cylinders firing against the same model while cylinders are off; 100 failed samples out of 200 give a Type B code. Mazda's 2.5 l four-cylinders store it when a deactivation oil control valve is clogged, for example by plastic from the filter wrapper (SA-061/20). In Honda's VCM V6 it stems from a rocker arm oil pressure switch, and the Hemi Ram 1500 got a PCM update for it. Bank 2 is P3497. The lamp comes on; misfires or rough running may follow.
- What you may notice
- Check engine lamp on
- Rough idle or misfire codes on the deactivating cylinders
- Ticking or clattering from the valve train
- Reduced-cylinder mode no longer used, higher fuel use
- Likely causes
- LikelyDeactivation oil control valve or its screen clogged by debris
- LikelyLow oil level, wrong grade or overdue oil change
- PossibleSwitchable rocker arm or lifter broken, dislodged or not latching
- RareOil pressure too high on cold start, e.g. weak relief valve spring
- RareEngine control software needing an update
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €80 – €4,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.