Circuit Description

Evaporative (EVAP) emission canister purge is controlled by a solenoid valve which allows ported vacuum to purge canister when energized by PCM. A vacuum switch in purge line is used to detect when system is being purged. PCM supplies and reads a 5-volt reference to switch. If switch is closed (no purge detected) when commanded by PCM, DTC P0441 is set.

Conditions required to set DTC are:

• No ECT, IAT, MAF, MAP, TP sensor DTCs set.
• BARO greater than 10 psi (0.7 kg/cm² ).
• ECT less than 237°F (114°C).
• IAT less than 158°F (70°C).
• Difference between ECT and IAT less than 18°F (10°C).
• Engine speed 550-5000 RPM.
• Canister Pulse Width Modulation (PWM) greater than 75 percent.
• EVAP vacuum switch remains closed (12-volt signal at PCM).
• TP sensor indicates throttle position between 2.5-52 percent.
• MAP greater than 10 kPa.
• Listed conditions present greater than 4 seconds.