P3458 code meaning
Cylinder 8 Deactivation/Intake Valve Control Performance
Powertrain system Generic code P34xx codes Check engine light
What P3458 means
P3458 describes a cylinder 8 that does not deactivate or reactivate as commanded although its control circuit is electrically fine. No manufacturer documents this code publicly. GM, the only maker with published cylinder 8 deactivation codes, files this failure under P349F on the L84: during a commanded skip, filtered manifold pressure stays above a threshold, which means the intake and exhaust valves kept working; the test runs with air charge above 120 mg and MAP/BARO between 0.30 and 0.95, and 22 failures in 25 opportunities give a Type B code. Bulletin 20-NA-204 adds that on 2021 full-size SUVs with L84 and L87 a voltage dip during cranking can set P349F without any hardware fault. Electrical faults are P3457, P3459 and P3460.
P3458 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyHard
- Typical labor0.5 to 12 hours
- Clears after repairAfter a drive cycle
Symptoms of P3458
- Check engine lamp on, sometimes going out again
- Shake or roughness in light-load cruising
- Misfire on cylinder 8 (P0308)
Common causes of P3458
- PossibleCylinder 8 deactivation lifter not unlocking or relocking
- PossibleOil pressure too low or oil aerated
- PossibleCylinder 8 solenoid valve sluggish or its screen blocked
- Less likelyFalse entry after low voltage while cranking, fixed by ECM update (GM analogue 20-NA-204)
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Cylinder deactivation solenoidLifterEngine oil
What each part of P3458 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 3 | Mixed range: generic and manufacturer-specific codes. |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| 58 | The exact fault in that area. |
What to do next
- Note P3458 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P3458
What does P3458 mean?
P3458 means "Cylinder 8 Deactivation/Intake Valve Control Performance". P3458 describes a cylinder 8 that does not deactivate or reactivate as commanded although its control circuit is electrically fine. It is a generic code, so it means the same on every make.
Is it safe to drive with P3458?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P3458 fail an emissions test?
Yes, it can. P3458 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P3458 to fix?
Difficulty: hard. A typical repair takes 0.5 to 12 hours of work. This is a job for a workshop.
Will P3458 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.