Powertrain, shared range

P3464 Cylinder 8 Exhaust Valve Control Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P3464 is stored once the line to a stand-alone cylinder 8 exhaust actuator sits at a high level, typically a wire touching battery voltage. No manufacturer documents this code publicly. According to GM bulletin 20-NA-038, cylinder 8 is switched off only by DFM engines and by the LTA and LT2, whose fixed pattern is 2, 3, 5 and 8; classic AFM uses 1, 7, 6 and 4. On those engines a single solenoid also moves the exhaust lifter, and GM lists a short to power on it as P3460: with the low-side driver commanded on, less than 0.5 ohm to supply, 20 of 25 samples, Type B. Its malfunction text says cylinder 7, a copy slip in the 2019 table. The shorted output cannot pull in, so cylinder 8 simply stays active. P3463 is the ground fault.

Likely causes

Control wire of the cylinder 8 actuator touching a battery feed
Shorted turns in the actuator coil, resistance far too low
Output stage in the engine control module failed

Symptoms

  • Check engine lamp on
  • Engine keeps running on all eight cylinders, slightly higher fuel use

Repair estimate

DifficultyMediumDIY possible
Parts and labour€60–900
Time0.5–4 h

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

Parts involved

cylinder deactivation solenoidwiring harnessecm

Related codes

P3461P3462P3463P3460P3497

References: law.cornell.edu, gsi.ext.gm.com, static.nhtsa.gov, static.nhtsa.gov.