Original BMW Crankcase Breather Return Hose, Cylinders 1 to 4, E39 M5 and E52 Z8 (2000–2003)

Original BMW oil separator return hose 11-15-1-407-344 carries crankcase vapor for cylinders 1 to 4 on the S62 V8 used in the 2000–2003 BMW M5 and Z8. BMW names the part a return hose and assigns it to the cylinder 1 to 4 bank, so it serves one side of the engine. It belongs to the positive crankcase ventilation system, which routes vapor from the crankcase back into the intake to be burned. Along the way the air and oil separator pulls oil out of that vapor and lets it drain back to the engine, while the cleaned air joins normal combustion. This hose is made in Germany and sold individually.

Original BMW Parts carry a 24-month parts warranty.

Because the hose lives with constant heat, crankcase pressure, and oil vapor, it is a common failure point in the S62 ventilation system. Oil gradually breaks down rubber and plastic, connectors grow brittle, and a split hose lets unmetered air into the intake. Typical signs include visible cracks or a broken connector, a check engine light for an intake air leak or another airflow fault, rough running or a misfire when the leak is severe, and oil residue on the hose, engine block, and nearby parts. In bad cases you may smell burnt oil and need to degrease the area to find the exact leak. BMW shows production of this number from September 1998 onward, shared between the E39 M5 and the E52 Z8.

Technical Details

• Manufacturer: BMW (Original BMW Part)
• Part number: 11-15-1-407-344
• BMW part name: return hose, cylinders 1 to 4
• System: crankcase ventilation and oil separator
• Engine: S62 V8
• Production start: September 1998
• Made in Germany
• Sold as one piece
• Warranty: 24 months

Common Questions

Does this hose fit both sides of the S62 engine?
No. BMW assigns this return hose to the cylinder 1 to 4 bank only.

Can a cracked oil separator hose set a check engine light?
Yes. Unmetered air from a failed breather hose can trigger an intake air leak code or another airflow-related fault, and a severe leak can cause a misfire.

Is this the same hose for the M5 and the Z8?
Yes. BMW uses this one part number on both the E39 M5 and the E52 Z8 with the S62 engine.

Fitment & Compatibility

Check the table below for the exact year, model, submodel, and any listed notes. PMB Performance can confirm this against your VIN, backed by more than 20 years of parts and fitment work.