Powertrain, shared range

P34A1 Cylinder 10 Deactivation/Intake Valve Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P34A1 would mean that cylinder 10 kept opening its valves while it was supposed to be deactivated. No manufacturer documents this code publicly; it only makes sense on V10, V12 or W12 engines. Lamborghini, for instance, gave the Aventador LP 700-4 a Cylinder Deactivation System that rests one bank at speeds under 135 km/h, but no public diagnostic table lists P34A1. The physics of a check is shared with smaller engines: Ford's patent US8667835B2 watches the rise and fall of manifold pressure across successive intake events and compares it with the commanded pattern. Causes would mirror those of the V8 codes P3498 to P349F: a stuck switching element, a faulty oil control valve or poor oil. P3474 covers the control side of cylinder 10.

Likely causes

Switching element of cylinder 10 not unlocking
Deactivation oil control valve sticking
Oil level too low or oil aged

Symptoms

  • Check engine lamp on
  • Reduced-cylinder mode no longer offered
  • Uneven running at low load

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€150–6,000
Time1–16 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

liftervalve traincylinder deactivation solenoidengine oil

Related codes

P3474P3473P34A0P34A2P0310

References: law.cornell.edu, patents.google.com, newatlas.com.