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This DIY gives some easy steps to begin diagnosis of problems in the EVAP system in New Beetles with the 2.0 liter engine. A hand operated vacuum pump can be used to do a check on the purge valve and the leak detection pump.

Here are the DTCs related to the EVAP system:

P0440 Evaporative Emission Control System (EVAP) - Purge Malfunction B
P0441 Evaporative Emission Control System - Incorrect Purge Flow A
P0442 Evaporative Emission Control System - Leak Detected (small leak) B
P0443 EVAP Purge - Circuit Fault A
P0452 Evaporative Emission Control System - Pressure Sensor - Low Input B
P0453 Evaporative Emission Control System - Pressure Sensor - High Input
P0455 Evaporative Emission Control System - Leak Detected (gross leak)
P1470 EVAP Emission Control System L.D.P. Circuit - Malfunction A
P1471 EVAP Emission Control System L.D.P. Circuit - Short to B+ A
P1475 EVAP Emission Control System L.D.P. - Malfunction Signal Circuit open A
P1476 EVAP Emission Control System L.D.P. - Malfunction/Insufficient Vacuum A

The MIL light triggering is indicated by the letter after each description:

A=MIL Triggered on first occurrence
B=MIL Triggered on second occurrence

The following youtube video gives an overview of the function and diagnosis of the EVAP system:

Volkswagen Evaporative Emsission Systems (EVAP) - Operation and Testing - Diagnosing - YouTube

Now, for the DIY. You will need a hand operated vacuum pump like those commonly used to bleed brake systems.

1. Remove the engine cover. Free the throttle cable (if present) from the clips at the points marked "A" and move it out of the way. "B" is the vacuum line going to the EVAP leak detection pump inside the right rear fender. "C" is the vacuum line to the EVAP purge regulator valve (N80). The vacuum line "D" is for the fuel pressure regulator. It is good to check its condition since this is a common source of vacuum leaks. The original lines are about 1/2" too short and tend to develop cracks.

evap1.jpg

2. Free the spring clamps and remove the two hoses from their tubes. The hoses are shown here freed from their connections. "A" is the leak detection pump line and "B" is the purge line. Be careful removing hose "B" as the line it connects to is plastic and may be fragile.

evap2.jpg

3. Use adaptors as needed to fit the vacuum pump line into the leak detection pump hose. Pump down to a 20" vacuum and make sure it will hold for about 30 seconds. If the vacuum doesn't hold then there is a leak in the line going to the leak detection pump or the pump is bad.

evap3.jpg

4. Release the vacuum and move the vacuum pump to the purge hose. Pump down to 20" vacuum and make sure it will hold for about 30 seconds. If the vacuum doesn't hold then there is a leak in the line going to the purge valve or the purge valve is bad.

evap4.jpg

5. Reconnect the vacuum hoses with their spring clamps. Reattach the throttle cable (if applicable) and replace the engine cover. Here is the location of the EVAP purge regulator valve (N80), marked "A".

evap5.jpg

Finding leaks from other sources is more complex and will need to use the techniques shown in the attached video. Generally, the EVAP canister is prone to damage and should be checked for cracks. Also, all the lines that run to the leak detection pump or EVAP canister should be visually checked.
 

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This was extremely helpful, thank you for posting it. Turns out my purge valve was malfunctioning. When I bench tested it, if I gave it a little smack, it would hold but after a few activations it would lose the seal.

New part on order.

Thanks again!
 
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