Evaporative Emission System High Purge Flow
Indicates that the purge flow from the EVAP system is excessively high.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The computer is detecting too much fuel vapor flow from the charcoal canister to the intake manifold, which shouldn't happen this much under normal conditions.
What the computer is actually seeing
The powertrain control module (PCM) monitors the purge flow during a specified test. It expects a certain vapor flow amount; exceeding that indicates something's wrong, like a leak or stuck component.
What a healthy reading looks like
Normal purge flow levels are typically around 0.5-3.0 grams per second; anything significantly higher triggers this code.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Check the wiring and connector to the purge valve for corrosion or loose connections. If faulty, repair as necessary.
- 22. Inspect the EVAP hoses and canister for damage or cracks. Replace any that are damaged.
- 33. Test the purge valve operation. Disconnect it from the harness and apply battery voltage; it should click and operate. If it’s stuck open, replace it.
- 44. Perform a smoke test to check for EVAP leaks in the system. If leaks are found, repair them and clear the code.
- 55. If all components are okay, consider scanning for other trouble codes that might indicate PCM issues.
Common causes
- Stuck open purge valve
- Damaged EVAP canister
- Hoses or lines cracked/blocked
- Defective PCM
- Leak in EVAP system
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Yes, it’s generally safe to drive, but fix it soon to prevent emissions issues.
Will this code come back after clearing?
If the underlying issue isn't fixed, the code will likely return after a few drive cycles.
Why does this code sometimes appear with P0455?
P0455 indicates a large leak, which can cause excessive purge flow, triggering both codes.
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