Help with 2002 Mazda Mellenia (Error Codes)

[PirateZHP]

Hey guys... I know this is not a ZHP... hell, it's not even a BMW. But we have some smart people on here and I need help.

Stephanie (my fiancé) has a 2002 Mazda Mellenia with 50k miles on it. This morning the check engine light comes on and flashes at her. She takes it to autozone and gets the codes... here they are.

P0303 - cyl 3 misfire
P0306 - cyl 6 misfire
P0421 - Warm up catalyst efficiency below threshold
P0455 - Evaporation Emission Control System Leak Detected (no glow/large leak)

So here's the deal... I am not worried about the two first codes. I got those. I do not know about the second two. In my internet searches, it looks like it could be a couple things: 1)Catalytic Converter 2)O2 sensors (there are 4)

If that makes sense to you, great... moving on... how do I figure out exactly what it is and how to fix it?

Thanks!

[Newjack]

Hey guys... I know this is not a ZHP... hell, it's not even a BMW. But we have some smart people on here and I need help.

Stephanie (my fiancé) has a 2002 Mazda Mellenia with 50k miles on it. This morning the check engine light comes on and flashes at her. She takes it to autozone and gets the codes... here they are.

P0303 - cyl 3 misfire
P0306 - cyl 6 misfire
P0421 - Warm up catalyst efficiency below threshold
P0455 - Evaporation Emission Control System Leak Detected (no glow/large leak)

So here's the deal... I am not worried about the two first codes. I got those. I do not know about the second two. In my internet searches, it looks like it could be a couple things: 1)Catalytic Converter 2)O2 sensors (there are 4)

If that makes sense to you, great... moving on... how do I figure out exactly what it is and how to fix it?

Thanks!

Fix the first two codes. The Misfire codes. Let's say its a bad spark plug or coil pack. If you don't have a spark and your fuel system is still delivering fuel to a cylinder that isn't burning that fuel, you get a lot of fuel leaving trough the exhaust valve and passing through your catalytic converter. This is bad for you catalytic converter as large(er) amounts of fuel were never intended to pass through it. The other two codes might just be related to the misfire codes.

I'm not a mazda guru and I haven't researched any of those codes, but since I'm on my way into work I just wanted to drop my two cents.

Good luck!

[PirateZHP]

Great advice. That may be the cheaper way to go about it as well. The problem I have in believing that that is the problem is that the car has such low mileage on it. I wouldn't expect coils or spark plugs to go bad...

[Newjack]

Great advice. That may be the cheaper way to go about it as well. The problem I have in believing that that is the problem is that the car has such low mileage on it. I wouldn't expect coils or spark plugs to go bad...

Yeah it is strange. Swap coil packs with different cylinders. If the code moves around then you know it's the coil pack. If not then its something else.

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[Avetiso]

+1 on fix the misfire first. O2 sensors shouldn't go bad that fast, and certainly cats should last longer.

[Johnmadd]

Yeah it is strange. Swap coil packs with different cylinders. If the code moves around then you know it's the coil pack. If not then its something else.

Sent from my Nexus 4 using Tapatalk

+1
Also, you can unhook the plugs one at a time and hold it close to the engine and have someone bump the ignition and you can see if it has spark physically.

[PirateZHP]

+1 on fix the misfire first. O2 sensors shouldn't go bad that fast, and certainly cats should last longer.

+1
Also, you can unhook the plugs one at a time and hold it close to the engine and have someone bump the ignition and you can see if it has spark physically.

Alright... looks like I will go that route first. Like I said, it is cheaper and easier than the other fixes. The problem is (and I have read) that if the O2 sensor is bad, it can work in reverse as well and set off the misfire codes.

[PirateZHP]

Bought plugs, wires, coil for the mazda this morning. They will be at the store at 1. It will be warmer then and I will do the work, reset the computer and see what happens.

[fredo]

Any updates ?

[PirateZHP]

Any updates ?

Well... So here's the deal... I got the wires and plugs in. The coil did not go in. I couldn't get the screws loose on the old one. I tried everything... wd40, pb blaster, heat, etc. So, I figured I'd go with what I could do. Car runs great now. There is no CEL right now, but we'll have to wait and see if it comes back.