I have two pending codes that are making my emission light stay on 1)P0410 and 2)P0491 I busted passed my sticker a month ago and I just did oil. Since the light came on went to two places to see what's wrong and both gave me those codes. The day I received codes I replaced filter,spark plugs,and sprayed carb cleaning to. Heck hoses for leaks and did not see any. Now I'm stumped trying to fix myself. Any help is greatly appreciated. Thank you
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2007 Mercury Milan Question: ?? emissions light stays on?
Answer #1lightsaber May 07, 2014, 16:41Journeyman
Both codes refer to the secondary air system that injects air into the exhaust manifold for 13 seconds after start up. Most likely your secondary air diverter valve is leaking internally and needs to be tested and replaced. This diverter valve is above the transmission under the hood, drivers side, and the air injector pump feeding air to the valve is below the fan. After you fix the secondary air system, you need to clear the codes, and complete a drive cycle to reset the monitors for the emission test.