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Discussion Starter #1
They disconnected my battery and then reconnected it at the body shop (minor accident - had to replace driver's door). Now, my Catalyst and Emission monitors are "Incomplete" and I can't pass the (California) smog test.


I need the drive cycle for my 2006 MDX so I can get my monitors in the OK status. Can't find it anywhere. Can't find it online. My dealer doesn't have a clue.


Is there a specific drive cycle for a 2006 MDX? If so, what is it? If not, what is the best generic drive cycle I could use? I am getting dozens of different answers this question. I would appreciate one that will get the job done for me. ;)
 

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There is no specific drive cycle - this should help you understand how the readiness indicator is reset after a battery disconnect...

 

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Discussion Starter #3
This says to attach a code reader and then drive the vehicle "under stop-and-go conditions with short periods of steady cruise" for about 5 miles and then "the readiness codes should switch to passed." I have driven my MDX under those conditions for 200 miles as instructed by my smog guy, and the monitors are still not ready.

I wish it was that easy, but I know it is not. Perhaps someone else may have more information on this but thanks very much for the input.
 

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Then it's not simply a drive cycle issue - there's something else that's preventing your readiness indicators from setting... Maybe you've got a failed downstream O2 sensor or bad cat?
 

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Discussion Starter #5
Right - a failed downstream sensor. What, pray tell, is THAT? And I don't even own a cat (or a dog, for that matter), so it couldn't be that.


Seriously - last Feb. my wife's car wouldn't pass smog due to INC sensors. We drove it and drove it and it still would not snap in. Finally, in frustration, we turned it over to our mechanic, who got it ready in two days, simply by driving it for longer distances than we had. In that case, it WAS simply a drive cycle issue and I strongly suspect it's the same thing here.


I really don't know what a downstream sensor is? What is it and how do I check to see if that's the problem?
 

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There are four sensors on our car, two on each bank of exhaust.

The "upstream" (pre-cat) sensors sniff the exhaust as it comes out of the engine, but before the catalytic converters. They're what tell your engine management computer to enrichen or lean out the fuel flow.

The "downstream" (post-cat) sensors sniff the exhaust as it exits the cats, and will throw a code if it senses too much nasty stuff coming out.

There's little to lose with a longer drive to see if it clears the condition... just find a great restaurant 20 miles away and have fun! ;-)
 

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Discussion Starter #7
Well, thanks. I have already driven the car almost 400 miles and I am pretty sure I could drive it 4,000 miles and it still would not be ready. There is more than a little to lose - my registration is due August 8th. I have to get the problem solved by then. If not, no tags.
 

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You need to check to see if there are any OBD codes stored in your vehicle - that should at least indicate which sensor it is that's throwing a fit. Otherwise, there are just too many possible suspects to start replacing parts. Often, you can get a free OBD reading at an auto parts place (I think Autozone does this as a service for their customers).
 

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Discussion Starter #9
I guess I forgot to mention - I have my own OBD code reader, two of them in fact.

My code reader says there are "0" codes stored in my car. I went for my second drive cycle this morning and now I only have one sensor that is not ready. The Cat sensor now says OK. I am going for another drive cycle tomorrow morning which I hope will do the trick. I have the type of code reader that lists all the monitors and tells you whether they are "OK," "N/A" or "Inc." The one, remaining "Inc" sensor is the Evap sensor.

Does all of this tell you anything?
 

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It only tells me that "something" in the rat's nest that is our evap system is not working right. The easiest thing to check is the gas cap (look for a problem with the gasket, or debris around the fill tube where it contacts the gas cap gasket). FWIW, here in Arizona, you pass if you're showing only one readiness indicator as "not ready"... not sure if CA is that way (probably not... it's CA after all). ;-)

Probably the most common problem other than the gas cap would be the PCV valve, and it's dirt cheap and dead easy to replace. Maybe a good thing to try if you don't have a better target...
 

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Discussion Starter #11
What about simply driving another drive cycle or two? My understanding is that once a battery is dis/re-connected, all it takes to get all the sensors back on track is driving the car until the sensors show OK. My smog guy tells me that when there is a battery dis/re-connect and the Cat and Evap sensors go out, it doesn't mean there is anything wrong with either of the engine parts involved. It only means that the OBD is unable to test those components, which is why you have to drive the car in order to get things right again.

You seem to imply that there is something wrong with the Evap system itself. I'm not so sure. There wasn't anything wrong with the Catalytic Convertor. It's sensor "came back" after I drove the car enough. I think the Evap sensor just needs a bit more driving.

I will make sure the gas cap is secure. Yes, in CA, everything has to be in a ready status.
 

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It may well reset if you drive, but given the fact you've done at least 400 miles, I have my doubts. Hopefully, your evap indicator will pop back to ready... if not, you're going to have to figure out what seems to be wrong with it. I know my own evap shows as "not ready" pretty often, but I don't worry about it because a) I can pass emissions with one not ready indicated, and b) the whole system is kind of pointless anyway.

Good luck - let us know if it does (or doesn't) clear up in the next week or so.
 

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Discussion Starter #14
Status report Sat. morning. Went for my third, drive cycle trip this morning - early. Did all the steps you outlined in your post on this thread. The evap sensor still shows "Inc." Question: if the problem here is something other than merely a lack of readiness which can be cured with the proper drive cycle(s), wouldn't a problem code show up? My code reader is showing 0 problem codes, which indicates to me that I just have to be patient and keep doing drive cycles. No?
 

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Discussion Starter #15
THIS JUST IN! In early afternoon yesterday, following my last post, I decided to drive up to smog guy's place of business and chat with him about the status of the problem, whine some about why things were not resetting, etc. I pulled in just as he was closing up. I told him that I had been able to get the CAT monitor to reset and now I only needed to get the EVAP monitor to reset - it was still out. He said, "Oh, well, if your only remaining monitor is the EVAP, I can certify your car. Bring it in on Monday." Great! I plan to do just that.

I still have a little trepidation, however, because everything I have seen on the subject says that California is a no tolerance state when it comes to unset monitors - that they ALL have to be ready. What smog guy said doesn't seem to square with that. Anyway, we'll see. Keep ya posted.
 

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Discussion Starter #16
So I went out and tried another (my 4th) drive cycle this (Sunday) afternoon. BINGO! "MONITORS INC 0." Looks like we're (finally) good. Will report in when the smog certificate is in hand.
 

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Discussion Starter #17
I have the smog certificate. My car passed the test this morning. All monitors ready - no problem. Game over. Thanks for all your support. I hope this never happens again - it's a nightmare.
 

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Whoo hoo! Congratulations on the good result. I have had cars that seem to have a mind of their own when it comes to setting the readiness indicators - but they always came around to my way of thinking eventually! ;-)
 

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A little bit of a bump... but, how long were your drive cycles? I am wondering if I just haven't gone far enough on one single drive cycle. I've driven almost 400 miles since resetting the codes and Evap is still showing "Incomplete". But I have not gone any long distances at one time (25+ miles).
 

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Here is the trick on evap:

1. The gas tank cannot be below approx 1/8 or above approx. 7/8 full or evap test will not run. I always advise between 1/4 and 3/4 to be sure.

2. With the proper amount of gas in the tank (above), let the vehicle sit overnight to stabilize temperature and pressure in tank.

3. Next day, start the vehicle and let it idle for 5 minutes before driving it.


If nothing else is wrong, the test should complete.

Note that a vehicle with only the evap test showing incomplete WILL PASS emissions testing.

Reference:http://asktheref.org/About/MonitorReadinessConcerns/tabid/552/Default.aspx
 
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