Powertrain, shared range

P3446 Cylinder 6 Exhaust Valve Control Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P3446 stands for an exhaust valve on cylinder 6 that does not follow a deactivation or reactivation command although its circuit is intact. No manufacturer documents this code publicly. GM watches a closely related failure under a code of its own: on the 2019 L84, P318E (Cylinder 6 Trapped High Pressure Exhaust Charge) looks for an exhaust valve that fails to open and let the burned gas out, recognised by crankshaft jerk in 66 of 100 samples, Type B, with immediate protective action. A Ford patent covers the opposite case, an exhaust valve that keeps opening after shut-off, detected from exhaust pressure. The electrical codes for this exhaust channel are P3445, P3447 and P3448.

Likely causes

Exhaust lifter of cylinder 6 switching late or not at all
Oil pressure too low for reliable switching
Exhaust control valve sticking

Symptoms

  • Check engine lamp on
  • Knock-like noise or vibration when the cylinder is switched back on
  • Possible misfire on cylinder 6 (P0306)

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

P3445P3447P3448P3442P349DP0306

References: law.cornell.edu, gsi.ext.gm.com, patents.google.com.