I fixed P0420 for a 2000 Corolla before

You have replaced the spark plugs. But have you ever checked your Mass Air Flow Sensor? By removing the two screws, located on plastic pipe between air cleaner to throttle intake, please take a look at it. There is a little filament that reads airflow, it should be orange in color; Due to age and mileage, this filament could be covered with dirt/oil and cause fauls reading.

I fixed a 2000 corolla with the same P0420 before, it was this Mass Air Flow Sensor. After I spray the filament with electrical cleaner, the check enginer light never comes back.

所有跟帖： 

• 这个容易，不妨一试 -色大胆小- ♂ (0 bytes) () 11/12/2012 postreply 13:53:09

• OK.这个我会再搞一下 -满地找牙- ♂ (0 bytes) () 11/12/2012 postreply 16:22:33

• 这么做其实是增加了空气流量，是吗？ -史迷- ♂ (0 bytes) () 11/12/2012 postreply 17:09:43

• MAF不敏感,电脑应该少给油,好像应该是饿死猫,不是富死猫 -满地找牙- ♂ (51 bytes) () 11/12/2012 postreply 17:34:30

• MAF的热敏电阻有灰尘覆盖时，我的车曾经system too lean -PolyGM- ♂ (0 bytes) () 11/12/2012 postreply 17:50:44

• With a dirty MAF, you probably will get a "system too lean" code -hardtofix- ♂ (850 bytes) () 11/12/2012 postreply 20:21:34