scheck engine light on on 2001 Mercedes-Benz ML320

what is evap emission system/vent control system. my check engine light is on and thats what autozone told me after they plugged it up to machine. also what is a speedsensor A?

by in Rochester, NY on February 02, 2011
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1 answer 1 comment
ANSWER by , February 02, 2011
Gas vapors from the fuel tank are stored in a canister (rather than allow these pollutants to be vented to the atmosphere) under certain engine running conditions these gasses are drawn into the engine where they are burned. The evaporative emission system can set a code foe many reasons and needs to be properly diagnosed before just replacing parts. The system is diagnosed using "smoke" or vacuum and a scan tool can open and close solenoids to check their operation. Not sure with Mercedes but speed sensor codes are a sensor on the transmission used to operate the speedometer, cruise control, traction control and or transmission controls.
COMMENT by , February 02, 2011
thamk you that helped alot..