P349ECylinder 7 Deactivation/Intake Valve Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P349E covers cylinder 7: deactivation was commanded, yet the cylinder kept its valve events. In GM's DFM design the intake lifter is unlocked first, while the exhaust lifter can only release once its cam lobe is back on the base circle; a sluggish pin therefore tends to leave the exhaust side working. GM's L84 and L87 check spots this through manifold pressure at each 90 degrees of crank rotation and stores a Type B code once 22 out of 25 opportunities have failed. Tula Technology, a specialist in skip-fire control, patented a check that combines intake pressure pulses with measured versus modelled crankshaft acceleration (US9891137B2). The wiring codes for cylinder 7 are P3449, P3451 and P3452. A driver may hear ticking and see the lamp.
- What you may notice
- Ticking from the valve train
- Check engine lamp on
- Cylinder deactivation inhibited, higher consumption
- Likely causes
- LikelySluggish locking pin, mostly in the exhaust lifter of cylinder 7
- PossibleOil solenoid of cylinder 7 not opening fully
- PossibleLow, thin or aerated oil
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €4,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.