Powertrain, shared range

P3470 Cylinder 9 Exhaust Valve Control Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P3470 covers a cylinder 9 exhaust valve that does not follow its deactivation command although the control circuit shows no electrical fault. No manufacturer documents this code publicly; J2012 reserves the codes for cylinders 9 to 12 for engines with more than eight cylinders. The risk behind it is described in a Ford patent: an exhaust valve that keeps opening after shut-off spoils the gas cushion in the cylinder and can be detected from changes in exhaust pressure. The opposite case, a valve that stays shut on reactivation, traps hot gas under pressure. Neither the Lamborghini Aventador V12 nor the Huracán V10 publishes how their bank shut-off works, and Audi's V10 simply cuts injection and ignition, so this check has no known user. Electrical faults of the same actuator: P3469, P3471, P3472.

Likely causes

Exhaust switching element of cylinder 9 stuck
Insufficient oil pressure for the exhaust switch
Exhaust actuator sluggish

Symptoms

  • Check engine lamp on
  • Knock or jolt when cylinder 9 comes back in
  • Misfire on cylinder 9 (P0309)

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–3,500
Time0–12 h

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

Parts involved

cylinder deactivation solenoidlifterengine oil

Related codes

P3469P3471P3472P3466P0309

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