Cause
Blocked EVAP reference orifice
The calibrated orifice used as a reference when testing the evaporative system for leaks, blocked. The system checks for a leak by comparing against a known one — a precisely sized hole — so the reference is what gives the test its scale.
Blocked, the reference reads as no leak at all, which makes every genuine leak look smaller than it is, or makes the test impossible and stores a monitor fault. The component is often part of the leak detection pump assembly. Its position under the vehicle is what blocks it: dust, spray, and insects nesting in a deliberately open passage. Inspect and clear the orifice before condemning the pump, and note that it is calibrated — cleaning must not enlarge it, which would make every leak read smaller.
Typically a moderate job.
Codes this can cause (1)
Codes where this is a likely explanation first, rather than merely a possible one.
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Others who found this
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about Blocked EVAP reference orifice.