Circuit Description

Evaporative (EVAP) emissions canister purge is controlled by a solenoid valve which allows ported vacuum to purge canister when energized (purge on) by PCM. A vacuum switch in the purge line is used to detect when system is being purged. PCM supplies and reads EVAP purge vacuum switch signal. If switch is open (purge detected) when not commanded by PCM, DTC P1441 is set.

Conditions required to set DTC are:

• No ECT, IAT, MAF, MAP, VSS, system voltage, vacuum switch or TP sensor DTCs set.
• BARO is more than 72.3 kPa.
• Start-up IAT and ECT readings are 38-90°F (4-32°C).
• Difference between ECT and IAT is less than 12°F (7°C).
• Vehicle speed is less than 60 MPH.
• Fuel tank is between 10 percent and 90 percent.
• Fuel tank vacuum is greater than 6 in. H₂ O for 5 seconds.