How do I reset a check engine light?

Question

Help me! I have a 2004 Kia Spectra. I lost my gas cap and just replaced it. I've heard that the check engine light might reset itself, but if it doesn't, does anyone have any suggestions how to do it? I've heard that disconnecting the negative battery cable for 30 sec. or more might work. Does it? I cant get my smog check until its fixed. Thank you to whoever responds!

Answer 1

Look for the fuse and pull it instead. Is you pull the battery wire you might find that your radio doesn't work and needs a code.

Answer 2

Disconnecting the battery for 10-15 minutes will do the trick.  Autozone will do a computer scan and reset the computer as well.  This will be free.  

Answer 3

if you don't have an obd2 reader then you should go the auto zone and have them read it and they can shut it off for you too.

Answer 4

1 it can

2 disconnecting battery also can do it

3 it can be set by a auto shop with a computer

Answer 5

Autozone or any repair or parts store is not going to be able to fix this problem. Only driving your vehicle will reset the Check Engine light. read on...

As far as the "Check Engine" system and it's inspection... Depending on the year make and model of vehicle you own, this system is different. If you own a 1996 or newer vehicle you more then likely own a vehicle which is equipped with an On-Board Diagnostics system called OBD II, as opposed to an OBD I system which older vehicles were equipped with. The OBD II Diagnostic system is designed to monitor all aspects of your engine's emission conditions and report this information to a central database within it's computer. This information is processed and checked against the computers pre-determined values for various inputs levels and performance patterns. If any problems are found, the computer will determine whether to alert the driver or not. If a decision has been made to alert the driver of an emissions problem, the "Check Engine" or "Engine Malfunction" light will illuminate on the vehicle's dashboard. In more serious emission conditions the computer may even begin to rapidly flash the "Check Engine/Malfunction" light indicating to the driver, that the vehicle needs immediate diagnosis/repair attention.

Now here's what the smog test has to do with the OBD II system...Your vehicle is equipped with an OBD II computer AND a link to connect the OBD II computer to a Smog Check Analyzer or Data Scan Tool (available at most auto part stores). The OBD II link relays all "Check Engine" conditions along with stored Trouble Codes with in the center database, to the smog machine during the time of the smog inspection. If any codes are present which cause the Check Engine light to illuminate either regularly or intermittently, the vehicle fails the smog inspection. Here's the tricky part, not all computer codes illuminate the Check Engine light.

In fact I can say there are two types of codes, bad codes and good codes. The good codes are the "Readiness Flags". These Readiness Flags indicate that certain emissions systems which the OBD II computer has been monitoring have PASSED the test, indicating that those systems are working properly. Then there are the bad codes. The bad codes are actual "Trouble Code". These codes indicate that the OBD II computer has detected a problem with in the emissions system. The Trouble Code will specifically indicate the component and problem which was found. Newer vehicle's have very complex codes in the thousands.

A vehicle will fail the smog inspection if the proper "Readiness Flags" are not set. A vehicle will also fail the smog inspection if any "Trouble Codes" are present.(Regardless of whether the light is illuminated or not). So it is possible for a vehicle to fail the smog inspection without the "Check Engine" light on. "Readiness Flags" do not cause the "Check Engine" light to illuminate, but may cause a vehicle to fail the smog test.

Now here's the fix... in order to set all the proper "Readiness Flags" the OBDII system must complete at least one drive cycle (in some cases two or three).  A drive cycle is a sequence of internal tests which the OBDII computer runs while your vehicle is being driven. This insures all emissions systems are functioning properly. Only then will your vehicle pass the smog inspection. A drive cycle usually requires one week of driving.

I hope this information is helpful to you. If there is anything I can help with in the future, don't hesitate to e-mail us at http://www.SmogTips.com

Sincerely,

Alec -  SmogTips Support

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