Cause
Faulty EVAP switching valve
The valve that redirects the evaporative system between its operating paths — commonly selecting which tank or which section of the circuit is connected for purging or for leak testing. It is distinct from the purge valve and from the vent valve, and confusing the three sends a diagnosis to the wrong part of a system whose components all look alike and all sit within a metre of each other.
Its failures divide cleanly into electrical and mechanical, and the codes say which. Circuit codes — open, low, high — are about the winding and its wiring, and are diagnosed with a meter at the connector. Performance codes naming stuck open or stuck closed are about the valve body, and mean the module commanded a change and the pressure trace did not follow. Treating a stuck-valve code as a wiring fault is the usual wasted afternoon.
Where it sits determines what kills it. Underbody mounting means road spray, salt and stone impact, so a corroded connector or a fractured pigtail is more likely than a failed solenoid. Check the connector's condition and the harness where it leaves its clip before removing anything, because both are visible from underneath and neither needs the valve disturbed.
Typically a moderate job.
Codes this can cause (5)
Codes where this is a likely explanation first, rather than merely a possible one.
- P2418 Evaporative Emission System Switching Valve Control Circuit Open Likely for this code Moderate
- P2419 Evaporative Emission System Switching Valve Control Circuit Low Likely for this code Moderate
- P2420 Evaporative Emission System Switching Valve Control Circuit High Likely for this code Moderate
- P2450 Evaporative Emission System Switching Valve Performance/Stuck Open Likely for this code Moderate
- P2451 Evaporative Emission System Switching Valve Stuck Closed Likely for this code Moderate
Information, not instruction
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