P3623critical severityPowertrain
Cylinder Deactivation Lifter Stuck Activated
on 2010 BMW M3 E90 4.0L V8 S65 · RWD
What this code means
A cylinder deactivation lifter is mechanically stuck in the deactivated (collapsed) position. The affected cylinder is not firing.
Symptoms
- Check Engine Light
- Engine misfire
- Rough idle and vibration
- Reduced power
- Exhaust smell of unburned fuel
- Catalytic converter damage risk
Common causes
- Collapsed lifter mechanism
- Oil sludge jamming lifter
- Lifter roller bearing failure
- Oil pressure loss to lifter
- Excessive wear on lifter body
Diagnostic steps
- Identify which cylinder is deactivated permanently
- Check oil pressure at affected lifter
- Perform compression test on that cylinder
- Check for oil sludge
- Inspect lifter via valve cover removal if accessible
Repair notes
Replace collapsed deactivation lifter. This requires camshaft and lifter removal. Inspect cam lobe for damage. Full engine oil flush recommended.
🔌 Don't have a code reader?
Any of these will read and clear this code — pick by how deep you want to go.
Bluetooth code reader (~$25)
Veepeak OBDCheck BLE →
Pairs with your phone — reads and clears codes, live data.
Serious DIY (~$100)
BlueDriver Pro →
Enhanced codes (ABS, airbag, TPMS) plus repair reports.
Shop-grade tablet (~$300+)
Autel MaxiCOM MK808S →
Bidirectional tests, service resets, all systems.
As an Amazon Associate, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.
Other Powertrain codes on this vehicle
29CC
Misfire Cylinder 1
29CD
Misfire Cylinder 2
29CE
Misfire Cylinder 3
29CF
Misfire Cylinder 4
29D0
Misfire Cylinder 5
29D1
Misfire Cylinder 6
29D2
Misfire Cylinder 7
29E0
Lambda Additive/Idle Adaptation Limit, Bank 1
29E1
Lambda Additive/Idle Adaptation Limit, Bank 2
29E2
Lambda Multiplicative Part-Load Adaptation Limit, Bank 1