P2C91 — Crankcase Ventilation System - Hose B Disconnected
The ECM detects that crankcase ventilation hose B is disconnected based on pressure or vacuum signals. Unmetered air ingress and oil mist escape are possible.
General code reference. Confirm the definition and diagnostic procedure for your vehicle's year, model and engine. A stored code alone does not identify a failed part.
Affected components
- Crankcase vent hose b
- Crankcase pressure sensor
- Intake manifold
Possible causes to check
These are possible checks, not a ranked diagnosis. Follow the vehicle manufacturer's test procedure before replacing parts.
- Hose disconnected at fitting
- Hose split or perforated
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
Related codes
Sources
Check each reference's vehicle and model-year scope. General background links do not establish which fault is most likely on your vehicle.
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.