Service engine light is on and I have replaces the Egr valve 4 times and all coil pks and plugs and the egr cylinder! still wont pass emissions. could it be the O2 sensors
02 sensors or bad cat converter,go to auto zone they will scan it for free,then you will know what the problem is,instead of throwing $$$$ into it,if scan reads bank 1,replace all 02 sensors,it has 3.
it could be the O2 sensor, but most of the times after fixing any parts of the engine the light won't be off till you will reset the fuse box settings. some of my friends did that and it did work. some of them changed all the fusses and it worked. try that and it may work for you :)
This is common for 1997 up. I have a 1997 F150 and its vacuum leak. Go to autozone or some place that could have a computer check it.
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