Powertrain, shared range

P3460 Cylinder 8 Deactivation/Intake Valve Control Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P3460 reports a short to supply voltage on the control circuit of the cylinder 8 deactivation solenoid, found while the output is switched on. GM lists it for the 2019 L84: under 0.5 ohm between output and controller power, 20 of 25 samples spaced 250 ms apart, Type B, with the same 11 V and 425 rpm enable limits as the other cylinder 8 circuit checks. GM's table contains a slip here: the strategy column for P3460 speaks of the cylinder 7 solenoid, while code and component name cylinder 8. Typical causes are harness damage against a feed wire or a solenoid with shorted turns; the visible result is that the engine stops using cylinder 8 deactivation. Siblings: P3457 (open) and P3459 (short to ground).

Likely causes

Cylinder 8 control wire in contact with a voltage source
Shorted turns in the cylinder 8 solenoid
Faulty driver in the engine control module

Symptoms

  • Check engine lamp on
  • Cylinder deactivation inactive, 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

P3457P3458P3459P3464P3497

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