# P0446 on OBDii **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** defender, 90\ **Created:** [June 6, 2009, 10:10am UTC](https://community.cartalk.com/t/p0446-on-obdii/31481 "2009-06-06T10:10:30Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![ramisalh](https://avatars.discourse-cdn.com/v4/letter/r/bc79bd/32.png) [@ramisalh](https://community.cartalk.com/u/ramisalh)\ **Post date:** [June 6, 2009, 10:10am UTC](https://community.cartalk.com/t/p0446-on-obdii/31481/1 "2009-06-06T10:10:30Z")
I have a land rover defender 90 , on the OBDII scanner i have an error code P0446, what does it mean and how can i repair it? does this cuase the rpm to be not stable? ---
**Author:** ![hellokit](https://avatars.discourse-cdn.com/v4/letter/h/6a8cbe/32.png) [@hellokit](https://community.cartalk.com/u/hellokit)\ **Post date:** [June 6, 2009, 11:23am UTC](https://community.cartalk.com/t/p0446-on-obdii/31481/2 "2009-06-06T11:23:40Z")
The DTC (Diagnostic Trouble Code) P0446 is for: “Evaporative emissions system vent control system” has a fault. This is the system that prevents fuel tank fumes from escaping into the atmosphere (which all of us breath). The unstable rpm might be an effect of this. At certain times, captured fuel fumes and air are drawn into the engine to burn with the fuel which is injected. If the drawing of fuel and fumes isn’t controlled (such as, by an open valve, etc.), then, that throws other stuff off, and the engine can run erratically. ---
**Author:** ![superdave](https://avatars.discourse-cdn.com/v4/letter/s/47e85d/32.png) [@superdave](https://community.cartalk.com/u/superdave)\ **Post date:** [June 6, 2009, 11:31am UTC](https://community.cartalk.com/t/p0446-on-obdii/31481/3 "2009-06-06T11:31:52Z")
A majority of the time it is as simple as a loose or faulty gas cap but can also be a faulty evaporative canister or canister solenoid valve. First check the gas cap for tightness, inpsect the gasket on it and the tank where it seals. Replace it (cheap) if you suspect it. You may get lucky.