Hi, I'm hoping someone can help, I'm slightly confused. I have 2004 civic ex that is misfiring , and the strange thing..

When I first pulled the codes last week it was P0301 cylinder 1 misfire. Now the code is 71-1 misfire cylinde #1

I am just guessing this is OBD1 vs. OBD2? Or I actually have no idea why its getting two digit code with hyphen and then third digit now.. They seem to be same descriptions, but why the new code numbers? I swear I'm using the same scanner (ANCEL FX6000) and connector lol. Can anyone enlighten me , Thanks!

 

P0301 is the OBD-2 code for a cylinder 1 misfire. 71-1 is the OBD-1 code for a cylinder 1 misfire. Same code... different foundational series. No big deal. It is STILL a cylinder 1 misfire. Do a compression test.

 

I was just wondering as to why it's happening - since I'm using the same OBD2 scanner on the same vehicle.. last week I got the PXXXX codes, now the XX-X codes. It's mildly frustrating as now I see other DTCs HO2S sensor, EVAP.. and I search on the description and I can then see what the equivalent PXXXX code is that others post. What's going on with my scanner, bent pin? Should I try the ECM reset option - "communicating with ECU" seems to take longer now too. Would really like to understand why it has changed to these codes.

(I might start a new thread for my 04 Civic, soon. I did do a compression test and that looked good. Will post link to new thread and steps I have gone through)

Thanks

 

could just be a bad spark plug

 

Yup... quite possible. I have seen a spark plug with the ground strap collapsed all the way to the electrode... essentially shorting the spark plug and creating the misfire.

 

Yes it was the spark plugs , no more misfires!

(anyone know how I can get the PXXXX codes back on my OBD2 scanner? TIA)