Hi,

My service engine light came on today. I scanned the computer and got code 0801, Vacuum cut balve bypass valve. Does anyone know what this is before I take it to the dealer and pay their $70 diagnostic fee. Thanks.

 

Diagnostic Trouble Code 0801 points to a problem with the Vacuum Cut Valve Bypass Valve. The malfunction is detected when an improper voltage signal is sent to the Engine Control Module through the VCVBV. The possible causes of this problem include a defect with the wiring or electrical connector, or with the valve itself. The VCVBV is located under the car, near the rear left tire. It is near the Evaporative Emission Canister but not mounted directly on it.

The VCVBV is a solenoid-controlled air valve. You may remove it from the vehicle and perform a bench test. There are two air hose nipples on the valve. Fasten a length of clean rubber vacuum tubing to either nipple. Gently blow through the hose. The valve should be closed and it should be difficult or impossible to send air through the valve. Now use a pair of fused test leads to provide 12 volts to the electric connector. The polarity doesn't matter. With the VCVBV solenoid energized the valve should be open and it should be easy to send air through the valve.