This thread seems to have branched into several directions but I will check the light (I think it did come on when the ignition was turned to "on," before the car was started) when I see the car in a few days and also plug in my tester to see if any codes are stored.
Thanks for your reply.
"David Farber" wrote in news:jssmf8$m3s$ snipped-for-privacy@dont-email.me:
The Check Engine light should come on for a few seconds when the key is first turned to "Run" (when all the other dash lights come on), then go off again. This indicates that the ECM has successfully performed its Power On Self Test (POST). The on-time for the light depends on model and year, with at least some of the newest cars taking 15 or 30 seconds for the ECM to do its POST.
After that, the light will stay off until a problem of some kind is detected by the ECM. The problem may be detected during an explicit test of a circuit (such as a below-threshold cat, or an EVAP leak), or it may be detected on-the-fly (as with an oxygen sensor problem).
If an oxygen sensor is unplugged, I would expect the Check Engine light to illuminate with that error either 1) the instant the engine is running, or
2) as soon as the engine reaches operating temperature.
A MIL eliminator could have also been used if that's the sensor's plug. On the computer side of it there would be something else plugged in. It will provide the computer feedback that indicates that the O2 sensor is operating and measuring O2 within normal operating range post catalyst.
It appears that the OP's photo is of the sensor end of the connector. The vehicle side of the connector could be nearby. Or someone could have pulled it up and secured it someplace.
As someone else suggested, a MIL eliminator could be plugged into that cable. This is a circuit that simulates a good O2 sensor and prevents the ECU from generating an error code. So its possible that the vehicle end of the cable will be plugged into something and it will take an experienced eye to spot a non-standard piece of hardware.
Back in the old days, the fix for a loose or broken catalytic converter element for my VW Rabbit was to take it off the car and break the ceramic insert to smithereens and dump it out of the housing. I think the recommended tool for the job was a broom handle. As far as I know, it was a factory procedure at the time.
That's only because the old VeeDub engines ran cleanly enough that they could actually pass a sniffer test without any cat whatsoever. I know this from personal experience... the cat on my old Scirocco gutted itself on a long highway run across Ohio once. The exhaust got real quiet, then all of a sudden I saw glowing chunks of crap in my rear view mirror and the exhaust note went back to normal :) (this was after I'd already installed a Techtonics exhaust system. If I'd still had a stock muffler things would have probably been real rattly.) Passed emissions every year after that with nary an issue.
I seriously doubt that that is true any longer. That was the 80's; if nothing else, anything with a post-cat O2 sensor will require a functioning cat not to throw a MIL.
nate
Hasty generalization.
It's always entertaining to read how you came to believe what you think you know. . -----
- gpsman
Maybe I'm not understanding the big picture but wouldn't it be easy to spot an eliminator device because the O2 sensor would not be plugged into it? I guess this would all hinge on the fact that you would have to know which ECU cable the O2 sensor was supposed to connect to. I'm quite curious now to get to the root of this problem. (-:
Thanks for your reply.
You'd probably be surprised at how negatively people will react to glowing chunks of crap being spewed out your tailpipe. Then again maybe not. How hot does ceramic material have to get to start glowing? My guess is "pretty hot."
I loved my Scirocco - one of the best cars I ever had.
Hah. Well, by the time I realized it was happening, there wasn't a whole lot I could do about it, because stopping in 80+ MPH traffic to retrieve little bitty pieces of ceramic that have now ceased to glow and look kind of like pieces of gravel didn't seem to be a good idea.
nate
As an extra added bonus, your exhaust probably sounded more boss. :-)
The sensor end is easy to spot. Because the lead from the connector to the sensor is short and you know where the sensor is.
The ECU (wiring harness) end could be a few feet long. So its possible that this end could be relocated some distance from the sensor end. And tucked into some hard to get to corner.
To top it all off, we don't know what the eliminator looks like.
I only had a few minutes to see the car yesterday. I plugged in the scanner and there were no trouble codes to display. The check engine light worked properly with the ignition in the on position. When the car was started, the light went off.
I'm not sure when I'll have another chance to look at the car and solve the wiring mystery but thanks to everyone for sharing their wisdom.
It could just be an unused connector. Lots of cars have them.
why don't you turn on your newsreader's "threaded" mode and bother to read back on how the op arrived at that comment? [rhetorical]
Because I've followed the thread. What are you trying to say?
i'm "trying to say" that hovanian nailed it and that you didn't see that.
as for "unused connectors", no cars /don't/ have them in locations like this, only in the cabin or in the engine compartment. under the car like this is a huge "no-no". the aftermarket zip tie should have been a clue if nothing else was.
I didn't realize I'd entered a contest. Awfully sorry.
Then again, since it's not being used, and there is no code, it would appear to be unused, if you know what I mean. If you're saying there's a simulator in the circuit, I'll bet it sets a code eventually.
no, i don't "know what you mean". did you check what the sensor plug looks like? you can see that it's identical to the subject and different from the harness plug can't you?
why would you "bet" in ignorance when you could /know/ for certain??? the logic of not bothering to find out is the same as that of being happy to pay for blinker fluid and muffler bearings.
or maybe you can't see that and you think i'm being unfair. in which case, i'm sorry to have confronted you with reality if it makes you feel uncomfortable.
You know, this is just weird. How can I know for certain that it's going to set a code eventually?
Weirder still.
You've kind of gone off the tracks. WTF are you talking about?
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