Cel

[Emode]

got a cel last night and went to autozone today to get it cleared, like i have done many times. Of course its the usual idiot there who never has the right info and doesnt know what hes talking about. I was pretty sure it would be for the rear o2 sensor, since i am running catless, and ive had it before. It ame up instead as the pre-cat sensor i believe, the code was something like
P_421, (the underscore is the number i cant remember)
Im not sure if the codes are all the same for all proteges, i remember a thread awhile back that said some were different. Anyways i asked him if he would clear it for me like the usual, and he wont do it for me, says i have to go the dealership and check it out, then come back and have him clear it. I was like"your stupid" and left.
Since this isnt the normal CEL for me, does anyone know if its bad, or the effects it might be having?

 

[Emode]

pmub

 

[BlkZoomZoom]

Off the top of my head I believe that has something to do with a maf sensor fault......If it is the code Im thinking of its caused by unfiltered air getting maf sensor dirty. I'm not positive however.

 

[Emode]

well s***
any other info about this

 

[BlkZoomZoom]

My suggestion is put intake system back together and whatever else un-factry back and bring it to the dealer.

 

[Emode]

yeah.............
thats gonna be a problem for the most part
im confused though
if it is a pre cat o2 sensor for emissions, what is the relation to a dirty maf

and the intake itself is pretty much normal except for a panel k&n filter, with the bottom of the box opened up

 

[Emode]

so has anybody else been able to figure out information about this issue.
its kinda freaking me out.

 

[girth]

Yeah, I hope you get it figured out to Emode. I imagine this is going to delay your installation of Ion's race pipe until you get this rectified? I'd make a suggestion on what the CEL might be if I had a clue.

 

[t3ase]

Since the code's still up, go back to that place and find another person to come check the code (write it down) and then clear it. Once we know the specific code, we can tell you what it is for sure instead of guess all kindsa stuff to get you worked up.

 

[BremertonMSP]

^^^ Got to agree with T3ase.

Also, are you running a MIL eliminator?

 

[mazdaspeed45]

P_0421 is due to having a header or no pre-cat, Warm Up Catalyst Efficiency Below Threshold (Bank 1). I get it all the time. you can get a mil Eliminator, its just 2 resistors to bring you O2 sensor voltage back down to factory spec.. I am going to build my own but just havnt had time to figure out what resistors I need, Depending on the time I have tonight (2 jobs/and a girlfriend) I will get the resistance and figure out what resistors you will need and were they go.. Ill do a "HOW TO" on it for everyone.

 

[Emode]

thats very cool 45
so what your saying is that this CEL and the rear o2 check engine light is fixed by the same MIL eliminator? Cause usually i was getting the rear o2 cel light, but when i got this it freaked me out.
thanks for helping me clear this up

 

[mazdaspeed45]

Im not 100% sure what 02 sensor it is forsure.. (before or after the pre cat). Im thinking the one before the pre cat, but I could be wrong. .. I will find out tonight when I do some resistance checks.. Just hang in there, its not going to "hurt anything, might run you a little rich its just anoying to see that cel.. This weekend I went Snowboarding to JASPER on my way there my cel came on, I was watching my Air/Fuel gauge, I had my foot on the throttle about the same the whole time not acelerating just cruzin.. i noticed that it was running rich, so I plug in my Scan tool and remove the Code, the Air/Fuel started bouncing around like it would normaly when cruzin... NO Harm..

 

[Emode]

interesting
i had always wondered wether or not there was a limp mode when the cel light came on, i guess this proves it somewhat

 

[mazdaspeed45]

I started the HOW TO last night, except I will be leaving out of town till the end of the week for a training course.. Have it done by next monday.. mabey sooner

Chris

 

[JunkPunch]

I was like"your stupid" and left.

Still laughing about this.