Arlight, so I was 15 minutes into mortoring today and my car threw its first Service Engine Soon light ever! While I did not go into panic mode I did try to baby it as I needed to continue driving. I have finally arrived home and thought I'd give NAM a try before checking out the official channels.

Quite frankly I don't know what it could be but I have the growing suspicion it is my O2 sensor or something around there. This is because I got an aftermarket header and welded 'hi-flow' Magnaflow cat put on my car back in early March. This was all done with the stock exhaust system. I could be wrong but I think the problem might have to do with this. Unfortunately, I don't have an OBD reader. Is there anyway I can tell if its an exhaust leak without it? The thing that throws me off is if it is an exhaust leak why would it take three months for it to show up?

Of note: I am halfway through a Texaco filled tank of premium gas of which, when I filled it up, I reset the ECU cluster through the engine key/center console method. While I have done this before(the ECU reset) I'm wondering if it had something to do with the SES light.

Anyways, anyone have any pointers/tips before I make some calls tomorrow?

 

Its gotta be something stupid. My light has been on for the last year or so. Turns on, turns off, I don't know? Car still runs fine and I'm to lazy to fix it.

 

AutoZone will read the code and give you code number. Then look the code number up. ECU Codes Listing

 

Yeah that's what I'm thinking because as far as I can tell the car runs fine.

Thanks for the info!

 

Well, I have a check out appointment set with the guys who installed my header due this coming Tuesday so we'll see whats what. As a side note, I don't know if its the paranoia but it seems my once clearly audible and frequent burble is a tad muted right now

 

Well, for anyone interested, I got my car checked by Mach V in Sterling, VA as they did some work for me earlier this year. Finally got a chance to talk to Dan, the owner, who seems like a real cool guy and knowledgeable as well. So my Kudos to Mach V Anyways, they ran the OBDII check and if I remember correctly it was a "classic P0420." = Catalyst System Efficiency Below Threshold. Dan pointed out that the cause of the code error was probably my aftermarket cat that I had welded on when I installed my header.

 

So the SES/CEL light came on the day after I took it in. Haven't had it OBDII read yet, but I'm assuming its the same code(I really need to get a reader). While the light is on, I really haven't noticed any drop in performance at all, and its been almost a week since I had the codes cleared. In fact, I've seen my gas mileage go UP! This could because I might be subconciously driving a little more cautiously and not pushing the car as hard but I feel like I'm driving the car as I normally would. Oh well, time will tell but so far so good

 

This seems to be a pretty common problem with aftermarket headers. What seems to happen is the ECU is set to read a difference in the signals from the pre-cat and post-cat oxygen sensors. With the higher flowing header and cat, the oxygen sensor readings get too close to the same and the ECU spits out the code. RMW has a fix for it that would probably work with any hearder. Other vendors may have it as well.