Ugh. Was on the highway in cruise and the check engine light popped on. Is there anyone who will hook up and tell me why it's complaining and reset the light grata (as in no charge - I mean, it only takes 45 seconds if you've got the computer)? If not, can anyone working for a dealer or a shop tell me how much to do it? Alternatively, anyone know a user-serviceable way to check/reset check engine codes?
go to autozone, free also, if you just want to reset it without checking it, unplug your battery, press the brake pedal a few times, plug back your battery and it should be cleared
Thanks. I'd prefer to know why it went off, even though the car seems to be running fine and may have just been a hick-up. Will any Autozone do it free??
No kidding - I'm in Uptown, too, so if you've can check the code, that's probably WAY more convenient for me than hauling myself to an Autozone, especially since my schedule can get a bit crazy. Cool. Let's try to do that.
Big thanks to Taras for giving the read a shot with his laptop and ecuExplorer, but as he thought, it wouldn't read the older Sub ECU. So, stopped at Checker's on Hennepin (I visit them often, it seems) and they in fact handed me a gadget to pull the code and reset it and let me do it myself. Code was "P0420" and the gadget read: "Catalyst System Efficiency Below Threshold (Bank 1)" Can anyone give me some insight into what that might mean? The light came on while comfortably cruising down I94. Also, this might be important, I've got an STi air intake (NA) and a hose was split - probably for a couple months, but I forgot to put a new one on until a couple days ago, then last night the engine code (I'm sure a picture of the hose would help, but I don't have one, it's the second [of two] after the air filter on the intake, and it connects into something [don't know what] generally on the back of the engine on the driver's side). Car's been running fine, so I'm not too worried about it, and I guess I'll see if it comes back on or not. Also, what about Bank 1? Does that indicate some particular side of the engine? I did have a problem with my #3 cylinder not firing well/at all because either the coil pack or the wire or both went kaputz (fixed that this past week).
Also, what about Bank 1? Does that indicate some particular side of the engine? I did have a problem with my #3 cylinder not firing well/at all because either the coil pack or the wire or both went kaputz (fixed that this past week) hmm.......................................maybe this has something to do with it!
Yeah, if the cats have been removed you'd see this, but p0420 is also common on NA subarus that have aftermarket headers. Usually without the heat shields on the headers the cats don't stay hot enough to work as efficiently. It might also mean that your 2nd 02 sensor is going bad (maybe?). Anyway, I think your car would keep running ok with this cel, unless you need to go through emissions testing, then you'll fail that test.
on another note, I found this ... yay? http://www.scoobypedia.co.uk/index.php/Knowledge/OBDIITroubleCodeDefinitions
Yeah, on the OBDII cars there are 2 o2 sensors -- 1 before the cat and 1 after it. The ecu will check the differences between the two and if the differences become too close, the ecu will assume that your cat isn't operating as efficiently as it used to and then your CEL pops on.
I replaced the coil pack and bad wire on Mon - and reset the computer's code showing #3 misfires, did plugs and other two wires on Sat, this engine light came on Sun. night. So, could be related, but it's coming in a bit after the fact - thought maybe things readjusting - don't know how much the ECU's on these subie's learn and adjust themselves.
I was thinking it might be something to do with a sensor - particularly O2. Also considered that with that hose coming off of the air intake split open for so long and recently being fixed, that maybe things were readjusting a bit and it hiccuped just enough to pop the light on. I guess if it keeps coming on, I will maybe have to look into replacing the O2 sensor. We don't have emissions tests here in MN, as far as I know, so that's not a prob, but I don't like leaving things unresolved.
Well, I guess I haven't visually verified this, but I'm going to go with probably yes. The car hasn't been modified at all other than the STi intake, and if I didn't have them, I'm assuming I would have seen this code before. And while I'm not really a car guy, I seem to recall catalytic converters being standard equipment on any vehicle manufactured in the last, well, couple of decades at least, huh?
Oh, and reading about cat's on wikipedia I see something about O2 sensors taking a couple minutes to reach operating temperature - I had been driving for 1/2 hour at least before the check engine light came on; whether or not that is important information in this case I don't know.
Thanks, I've been a bit confused all along regarding the appropriate terminology for that "big blue tube that sounds really neat when I stand on the gas" Now I have to google it.
Update on engine code (lack thereof) A few hundred miles later, no code has reappeared. Hopefully just a hiccup, then, and nothing serious.
Here's most likely what happened. If you drive around long enough with a misfire, you can be dumping a lot of unburned fuel into the exhaust system. Which can destroy your cats over time. The code may never come back on, but sometimes it returns after a few thousand miles. If the light does come back on, your rear O2 sensor is saying, "your cats are not working up to par." It's up to you if you want to fix them.
Thanks for the info. I only first got any inkling at all that something was wrong with the firing on a Friday evening - but I don't know how long a problem might have existed without me noticing. I maybe put 50 miles or less on it before fixing it (which was the minimal amount I absolutely had to drive before I could make it to the dealer for parts on Monday), so hopefully the cat's not damaged. But we will see.
Well, the code popped up again today after about 45 minutes straight driving on I-94. I rarely drive for that long at steady highway speeds, so maybe the code is somehow related to that driving pattern. Any sure-fire way to test the o2 sensor? Roughly how much does a replacement cost? How hard is it to change - is it buried deep or fairly accessible?
If it's the P0420 code again, it's normal on slightly modded cars with as little as an exhaust, or CAI, or headers. Headers tend to be the biggest culprit, as aftermarket ones tend to lack heat shields. Chances are, if you wrap your headers, the code will go away for good. It's an emissions code, nothing more. It does not affect performance. My car has had this code on for about the last three years. In fact, I get concerned every few weeks when the CEL goes out on the dashboard. But it comes on again after a few miles, and order is restored to the universe. Stuart.
