P3428Cylinder 4 Deactivation/Intake Valve Control Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P3428 means the wire that switches cylinder 4's deactivation solenoid is tied to voltage. GM's bulletin 20-NA-038 lists cylinders 1, 4, 6 and 7 as the ones its AFM V8s switch to V4 mode, which makes cylinder 4 a standard candidate. In the 2019 documents for L84, L86 and the Corvette LT4, GM judges the circuit with the low-side stage switched on: a supply path of less than half an ohm counts as a short, and 20 bad results within 25 produce a Type B entry and the lamp after two trips. Because the low-side stage sinks the current, a line stuck at battery voltage can push the output into overcurrent, so after repair the module should be checked too. P3427 is the short to ground, P3425 the open. The truck or car keeps all cylinders running.
- What you may notice
- Check engine lamp on
- No V4 or reduced-cylinder operation
- Likely causes
- LikelyCylinder 4 control wire shorted to a 12 V feed
- PossibleLow-resistance winding in the cylinder 4 solenoid
- RareOverloaded output stage in the engine control module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €60 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.