# Preparing for Emissions Test and resetting codes



## jmandeville (Dec 5, 2005)

I have a 1994 Altima. My Engine light has been coming on because of EGR and Knock Sensor. I believe I have fixed these two problems and have reset the error codes.

Does anyone know what the criteria is for how much driving I must do before taking the car in for its Emissions Test ? I've heard that the ECM keeps track of having its codes cleared and that some amount of driving must occur after the codes have been reset and prior to arrival for Emissions Testing.

What exactly is this Criteria ?
1.) X# of miles driven, or X# of miles driven with engine temp above Y?
2.) X# of start-ups ?
etc.

If I buy a scan tool, will it tell me if I have driven the car enough for the ECM to consider that the problems have been fixed ?

Any recommendations on what scan tool to buy for a 1994 Altima ?

Thanks,

Jack


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## KraZThug (Dec 27, 2005)

jmandeville said:


> I have a 1994 Altima. My Engine light has been coming on because of EGR and Knock Sensor. I believe I have fixed these two problems and have reset the error codes.
> 
> Does anyone know what the criteria is for how much driving I must do before taking the car in for its Emissions Test ? I've heard that the ECM keeps track of having its codes cleared and that some amount of driving must occur after the codes have been reset and prior to arrival for Emissions Testing.
> 
> ...



Im not quite sure what the answer for your questions is, but if im not mistaken your car is a OBD-I i dont know what year+ is OBD-II but that will show you any error codes for any of your sensors + decode them. I dont know how much it is, it might be a little expensive but it can be very helpfull once you learn how to use it.


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## Darktide (Jul 29, 2004)

1996 on up used OBD II scanners. So this car would indeed fall under the OBD I's range. Just be careful which one you get. Most car stores I've gone through carry a company called "Actron" which is signified by a bright orange tool/packaging. You want to double check the list of vehicles that they apply to because there were several different models of the OBD I. Actron also sells a super tool that does all OBD I and II but that thing is a couple hundred dollars. But they won't let show you the information as to how long its been since you've cleared the code, even the supertool doesn't do that. As for how long after clearing you can go in and get the emissions test done... thats actually a state law and changes between them all so you'll want to just call a garage and ask them about it because you actually have a legitimate case they should tell you what you need to do. 

Darktide


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## jmandeville (Dec 5, 2005)

Thanks Darktide,

I live in New York State and this upcoming inspection will be a first for me where they hook-up to the car... It's got me a bit worried. Does anyone out there know what the folks that are performing these inspections are using for scanning equipment ? It sounds like whatever they are using has the ability to determine how much has happened with the car since the error codes were cleared. 

Thanks,

Jack


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## jmandeville (Dec 5, 2005)

I did some surfing today and I came across the following regarding the year of the vehicle where New York State will use the scanning of the On Board Diagnostics:

http://www.nydmv.state.ny.us/vehsafe.htm#einspect

The following is an excerpt:

_______________________________________________________________
Emissions Inspection for Gas-powered Vehicles
THE NEW NYS VEHICLE INSPECTION PROGRAM (NYVIP)
New York State has a new program for annual vehicle inspection (NYVIP).
The NYVIP is a program that includes a new inspection of the emissions control systems on gas-powered vehicles that have a model year of 1996 and newer. The NYVIP inspection also includes:
•	The current safety inspection, 
•	The current gas cap check, and 
•	The current visual inspection of the emission control devices. 
_________________________________________________________________

So if I am interpreting this correctly, New York State does not "scan" cars earlier than 1996.

Attached is another except from the same link:

________________________________________________________________
For NYVIP inspection, the NYS-licensed inspection station uses new equipment to monitor the on-board diagnostic system (OBDII) of your vehicle. The station uses the new equipment, a modem, and a dedicated telephone line to report the inspection results to the DMV. The dedicated telephone line must be an analog telephone line; it cannot be a digital telephone line.
The inspection station also uses the NYVIP equipment to conduct the inspections for motorcycles, trailers, and vehicles that have a model year of 1995 and older, but the station does not conduct the ODBII inspection for these vehicles.
_______________________________________________________________

Since the 1994 Nissan Altima has a OBD #1 instead of an OBD#2, then I guess this all makes sense.


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## KA24Tech (Feb 2, 2004)

I just posted this for another thread
The ECU is under the front of the console. The trim panel under the very front of the console on the driver's side. The ECU has a diagnostic mode which is activated by turning the ignition to the on position without the engine running and then turning the mode select fully clockwise for two seconds and then turn it back fully counterclockwise. Wait for the inspection lights, which are next to the mode selector on the ECU. All you have to do is read the long and short flashes (the first digit is the long flash(es) and the second set is the short flash(es). To get it out of diagnostic mode just turn off the ignition just make sure the selector is all the way counterclockwise.

To reset the ECU turn the mode screw to the fully clockwise position and hold it for 2 seconds and then back fully counterclockwise after entering the diagnostic mode 1. Or disconnect the battery for more than 24 hours.

Troy


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