Bonjour,

I need help ,Protege 2001 2 liter have a code 0300 and 0421 ,the car run fine untill i hit the highway when its reach over 100 km/h for a few minutes its start to run bad , if i remove my foot from the gas pedal and put back my foot on the gas pedal two second after it's run ok I change the spark plug but it didn't change a thing ,maybe cleaning the egr???

 

might be a clogged fuel filter or fuel pump

 

Where is the fuel filter?

 

Po421 is a warm-up catalyst efficiency below limit code. It means that your catalytic converter is not cleaning the exhaust of harmfull emissions as well as it should be. The P0300 is for random engine missfire detected and is probably the reason why you are getting the P0421 code. Engine missfires are very hard on the catalytic converter. Had an 02 Protege in a couple of months ago that was setting a random missfire code very, very intermittently. Finallly traced problem down to an ignitioncoil failing. Owner decided to replace both coils and have not heard back from since.

2001 Protege does not have a fuel filter unless you want to count the pick-up screen sock in the fuel tank with the pump.

 

Hi, thank you for your help.

Why a ignition coil will work intermittently?
Could i track down the faulty one?
should i buy aftermarket or dealer?
Sorry for my english writing...

 

i am happy that you are the king but that don't answer my questions

 

Do not know if you will be able to locate a coil aftermarket. Your engine does have the two coil on #2 and #4 cylinders with a plug wire running to #1 and #3 cylinders yes? On the one I had the problem with, the coils tested just fine resistance wise and there was only a failure once in a great while. The best way you are going to probably narrow down to which one might be the problem is to just replace one of them and drive to see if the problem goes away. If you replace the one on the #2 cylinder and problem does not stop then move the new coil over to #4 cylinder and reinstall the old coil originaly replaced back onto the #2 cylinder. Hope that works or at least makes sense.

 

Bonjour,

I just change my 2 ignition coils (autozone good prices) ,I ran for 50 km and no problem ,suddenly the check engine light pop up again but this time 0421 only so i erase it again whit my obd2 reader i'll run it again this week on a long trip to see if it's still pop up ,the problem occur only at high speed (over 100km) any idea?