27BB

What the code means

Code 27BB points to a fault in the exhaust VANOS control. The DME has detected an error in the VANOS solenoid circuit on the exhaust camshaft.

Normally the solenoid controls oil flow to the exhaust VANOS unit, and the DME monitors its operation through the circuit. If the circuit is open, the solenoid is stuck, or the DME itself is faulty, the system can no longer control exhaust camshaft timing. Possible causes are a stuck solenoid, a wiring break, or a faulty DME.

Symptoms

• Loss of power
• Rough idle
• Knock on startup
• Check Engine light on

Diagnosis and repair

1. Read fault codes with ISTA.
2. Check the exhaust VANOS solenoid: winding resistance should be in the 7–12 ohms range. A value outside that range points to a bad solenoid; if resistance is normal, look for a break in the wiring.
3. Replace the exhaust VANOS solenoid, part number 11367579072.
4. Check oil pressure: at idle it should be at least 22 psi (1.5 bar). Low pressure won't let VANOS work correctly even with a good solenoid.

The common diagnostic mistake is replacing the solenoid without checking oil pressure and wiring condition: if the circuit and power are fine but pressure is low, the fault will come back.

Secondary problems

• Ignoring the fault can lead to timing chain jump and valve damage — this is the most severe chain of consequences, and delaying the repair makes it worse.
• VANOS bushing wear is possible.