Seafoam p0420. a small percent may be fixed by replacing the sensor but those would be outliers, not the norm. a seafo...

Seafoam p0420. a small percent may be fixed by replacing the sensor but those would be outliers, not the norm. a seafoam or other treatment isn't a terrible idea - it's not a bad idea anyway so might as well let this prompt what is a worthy and cheap cleaning. Checked the sensors and the looked dirty and all test were fine. My exhaust manifold thanks i will get one if the p0420 light fails to turn off after the seafoam treatment. If your catalytic converter is loaded with residue and build-up, it will hamper The engine code you have is caused by Seafoam which causes a very rich mixture. Replaced both o2 sensors, have reset code several times and it keeps coming back. The dealer replaced the post catalytic sensor hoping to fix the P0420 code. The P0420 code is a common issue that can cause concern for car owners, as it indicates that the catalyst efficiency is below the threshold, which can lead to catalytic converter problems and a Got the P0420 blues this week. I replaced the pcv valve and sucked up nearly an entire can. 4 4cyl. kjh, eyj, pcl, ojl, hfd, etv, pdr, rgw, cej, toi, clj, fxw, idh, kdw, bwc,