Q: Check engine light in code P0418

asked by on October 07, 2016

Car running rough and cuts off sometimes when almost stopped check engine light code P0418 secondary air injector relay a malfunctuon we tested some things on the blazer checked the air pump fuse it was good replaced the relay and tested the air pump by the battery but then when you hook it back to the car it doesn't turn on and the connections look fine replaced the idler pulley but still needs serpentine belt

My car has 107000 miles.
My car has an automatic transmission.

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The air pump fuse is a 30 amp fuse that powers the pump. The "trigger" for the relay comes from the ignition switch, through a 10 amp fuse. Have you checked to see if the "trigger" wire to the relay is going to 12 v? If not, check the 2nd fuse and ignition switch path.

I would recommend having a certified technician, like one from YourMechanic, perform a rough idle inspection, and check your serpentine belt, to diagnose these issues, provide an accurate assessment of damages, and estimate the cost of repairs. YourMechanic can dispatch a mobile, professional mechanic to your location for diagnosis and repairs.

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