Q: CEL for PO303 PO404

asked by on December 20, 2016

Replaced plugs and wires, checked coil and it seemed to be fine. Not sure what to do. I want this CEL off.

My car has 112000 miles.
My car has a manual transmission.

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Do you mean P0303 and P0304 or an actual P0404? The 404 is for an exhaust gas re circulation valve problem where the valve may be clogged or the vacuum supply hose my be cracked. The coil may look ok, but if there is no spark at the post for cylinder 3 and the wires and plugs are ok, the problem may be in the coil. Consider hiring an experienced technician like one from YourMechanic who can come out and take a closer look at the vehicle and perform a few checks to offer a more personal diagnosis of your warning light.

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