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Alexm

Alexm 2/16/2019

2007 Volkswagen Beetle 2.5 5 Cyl 2.50L

Preventive Maintenance

07 beetle code P0442 help

I have a 07 beetle 2.5L. My check engine light is on for code P0442 I already changed the purge valve bc previously I had code P0445. Sadly a week later this new code appeared.I've already got a new gas cap(dealer)and reset the light and it almost automatically comes right back on....I still have rough starts after getting fuel and have noticed that my gas meter on my dash has been moving up as if I got gas(but I didn't)... Also not sure if it's relevant but when I undo my gas cap it sounds like a lot of pressure is shooting out.

1 Answer


Jimm

Jimm 2/16/2019

P0442 = Evaporative system small leak detected

The vehicle's PCM (powertrain control module) tests the evaporative emissions (EVAP) system for large and small leaks among other conditions. In the case of this DTC, it indicates a fuel vapor leak in the EVAP control system. It means a very small leak has been detected. In fact, the leak can be from a hole as small as 0.04" in diameter.
The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine to be burned. That results in decreased vehicle emissions.

A code P0442 most likely means one or more of the following has happened:
A loose or improperly affixed gas cap
A non-conforming gas cap (i.e. not factory/original brand)
A small leak/hole in a fuel vapor hose/tube
Other small leak in EVAP system
Faulty vent o-ring seal
Defective vent valve
Defective purge valve
Defective leak detection pump

With a P0442, the most common DIY repair is to: Remove and reinstall the gas cap, clear the codes, and drive for a day and see if the codes come back.
Otherwise, replace the gas cap (recommend an OEM original part, not aftermarket part), or visually inspect the EVAP system for cuts/holes in tubes/hoses.

More advanced troubleshooting steps include:
Using an advanced scan tool, perform an EVAP leak test
Verify operation of the EVAP purge solenoid / valve
Perform a smoke test to see where the leak is

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