Help! P0304 code

FoxyRoxy05

Member
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2003 Mazda Protege5
I drive an 03 Mazda Protege5, who has given me no problems. Last night, my check engine light started to flash and my engine had no power. I quickly got the codes (thank goodness for my Bluetooth OBDII reader) and got two codes - P0421 (I knew about that one) and P0304. From what I've looked up, I'm going to replace my wires, spark plugs and ignition coils. Should I check/ clean my EGR valve as well? If anyone has pics or schematics, I'd GREATLY appreciate it!
 
Replacing your plugs, wires and coils will probably fix your problem.

Cleaning your EGR may not be necessary.



 
Thank you for your advice! I replaced the plugs, wires and ignition coils, as well as clean the MAF sensor. I also cleared the codes and reset the ECU. The car seems to be running fine but it was a bit of a rough idle when I stopped at a light. Is it true the ECU might take some time to be back at 100%?
 
"Non-fouler trick"? Not familiar with that one ....

The "non-fouler trick" makes the ecu think you have a happy and healthy pre-cat, even if it's shot, or not there at all like if you have a header.





Drilling out the first one is a PITA !!...
 
A new pre-cat is about $130 US ... As long as you don't live in California or New York...

 
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