# Pass Emissions and Inspection with Check Engine Light on?



## Rspeters

Hi there, anybody know if a car can pass emissions and the safety inspection with the Check Engine Light on? In some states it's an automatic fail, I haven't dealt with it yet here, but my car's up for both and worried it's not going to pass. The check engine light is for a knock sensor.


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## DallanC

Pull the lightbulb for it









-DallanC


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## lifes short

The way I understand this is the cars computer system is what does the emission test now. The shops computer reads your cars emission sensors memory. If you have an emission related code in your computer memory it will not pass. The way I got around this was to stop by your friendly neighborhood auto parts store and borrow their code reader, after it tells you what codes are in the memory you can clear out all of the codes from the memory which turns off your check engine light. If you take your car in then it will not pass because it will not report everything ok until you have driven about fifty miles. My code problem must have been nasty gas because after I cleared the codes it never came on again. Drove for fifty miles and then had them do the emission again everything OK. Hope this helps


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## Mavis13

The light on is an automatic fail for us in cache county; pulling the bulb wont help because the tool that talks to the cars control control module knows the light is on and tells the tester that. The trick is to find out what code has the light on and then we can discuss what it takes to fix that. If it's for something dumb like the evap system sometimes just clearing the code like LS said is all it takes but usually it's more complicated. I got one for a knock sensor once; I replaced the sensor and that's all it needed.


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## DallanC

Wierd, I've never had a shop plug into the OBD for an inspection. Must not be a requirement in my county.


-DallanC


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## Rspeters

Mine's for a knock sensor, and it does come back on after clearing the code. Unfortunately, the knock sensors are $150 so I hate to change it unless I'm sure it's bad. Apparently for my car the wires can tend to get loose over time and cause the error...so I'm ok with it being there until I can properly fix it, but I'm just trying to figure out if it's going to affect the emissions test.


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## cklspencer

^Yes it will, codes need to be clear and the vehicle must go through a full drive cycle.


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## martymcfly73

What about exhaust leaks? Can a vehicle pass with one??


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## Huge29

I just helped my neighbor pass her test while her hubby is in Kuwait. Hers was one of those dumb emission codes that would stay off for a few days. We reset it and took it in the next day and it was still too recent, so she brought it right back the next day and it passed just fine. One of my cars does the same thing, so we just reset it two days before. One of those silly vacuum leak error codes.


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## Rspeters

Thanks everyone for the info. Just removed the knock sensor, cleaned it, put it back in and the light went on again so I guess I'll be ordering a new knock sensor. That thing was a pain in the butt to get to.


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## Fowlmouth

So, It sounds like if the engine light is on then you won't pass the emissions test, but it doesn't have anything to do with passing inspection? Is this correct? I live in a county that doesn't have emissions testing so I haven't had to deal with that BS.


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## Mavis13

This is our first year with emissions, but I had a shop fail mine for the check engine light several years ago. I removed the bulb, et voila, it passed. Now that we have emissions testing in Cache County they plug in to the ODBII and you got to have a happy PCM to pass.
Hold on; before you replace the sensor there's going to be a way to test it and the wires that connect to it. Google it; generally it can be done with a simple multimeter.


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## Rspeters

Well, after a bit more testing I ordered a new knock sensor and put it in....the check-engine light hasn't come back on yet, so I'm hopeful I fixed it. I'v driven it more than enough to let the computer reset.


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## Huge29

Here is probably the best $20 I have ever spent, if you do any wrench turning, I recommend you do the same, I have this exact model and it does it all. http://www.amazon.com/Autel-MaxiScan-MS300-Diagnostic-Vehicles/dp/B001LHVOVK/ref=sr_1_1?ie=UTF8&qid=1392437441&sr=8-1&keywords=obd+ii+scanner


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## Mavis13

I sprung for this one, it's a bit more but it tests the emissions system and shows you what the shop will be testing so there's no surprises.
http://www.harborfreight.com/can-obd-ii-deluxe-scan-tool-60693.html


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