- Code
- P0448
- Applies To
- Most makes, generic code
- Loose Cap Can Set It
- Not named in our sources
- Typical Fix
- $182 at YourMechanic
- The vent valve circuit looks shorted.
- A shop confirms it with the carmaker's EVAP test and a smoke machine before replacing parts.
- Usually yes for now, but get it fixed soon and check for open recalls.
What The Carmakers Call It
- EVAP emission system vent control circuit shorted, as printed by Volkswagen Group of America
Causes Named In Carmaker Bulletins
Our sources name the part this code points to but no single cause. Start with the Vent Valve guide.
No source ties this to the gas cap.
What The Fix Costs
The usual part for this code is the vent valve. Published estimates put it at $182 at YourMechanic. The full table with every source and date is on the cost page. A diagnosis first keeps you from paying for a part you did not need, which is why we price check engine light and smog check before the fix.
Getting The Light To Go Off
After the repair the light goes off once the EVAP test runs and passes on three drive cycles in a row, and the code is erased after 40 warm up cycles, per CARB. The test only runs under set conditions such as a fuel level between about 15 and 85 percent, so it can take days.
Related Codes
Author Source EEAT Authors · Anthony's Author Page
Sources For This Page
- Technical Bulletin 2034072, Canister Purge Valve N80 Diagnosis (July 18, 2013), Volkswagen Group of America, read 2026-11-12
- 13 CCR 1968.2, Malfunction and Diagnostic System Requirements, OBD II, California Air Resources Board (via Cornell LII), read 2026-11-12
- Evaporation Vent Solenoid Replacement, YourMechanic, read 2026-11-12