Cause
Blocked or kinked evaporative hose
A hose in the evaporative system crushed, kinked or blocked, so vapour cannot move along the path the module is testing. The system's monitors work by moving air or vapour and watching pressure respond, so a blocked line produces a pressure that changes too fast, too slowly, or not at all — and the code names whichever monitor noticed.
Its position under the vehicle is what fails it. These lines run from the tank to the canister and the vent, exposed to stones, salt and anything that contacts the underbody. A jack placed on a line, or a kerb strike, crushes one flat without leaving a mark anybody notices — and the fault appears days later.
Blocked and leaking produce opposite codes from the same area, so establish which you have before searching. Disconnect at both ends and blow through — it is a definitive test and takes moments. Check the vent path's filter and any open end for insect nests, which is a genuine and surprisingly common blockage in a system that is open to atmosphere by design.
Typically an easy fix. Often worth checking before paying anyone to look.
Codes this can cause (3)
Codes where this is a likely explanation first, rather than merely a possible one.
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