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 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, or TP sensor DTCs set.
• BARO greater than 10 psi (0.70 kg/cm² ).
• ECT less than 237°F (114°C).
• IAT less than 50-158°F (10-70°C).
• Difference between ECT and IAT less than 18°F (10°C).
• TP angle 2.5-55.0 percent.
• Engine speed 550-5000 RPM.
• EVAP canister Pulse Width Modulation (PWM) less than 3 percent.
• EVAP purge vacuum switch open.
• Listed conditions present for more than 4 seconds.