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post #1 of 22 (permalink) Old 02-25-2014, 05:03 PM Thread Starter
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Check Engine Light Wont Turn Off

Hey guys my check engine light recently went off for an emissions code and i replaced both of the parts that could have been causing the problem. After replacing them i disconnected the battery which i was told would reset it but, the light is still on and won't turn off. Any ideas? I was told i might need to take it to a dealer to get a master resets but before i do that i want to see if there was anything else i could try.
Thanks guys!
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post #2 of 22 (permalink) Old 02-25-2014, 05:19 PM
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I know for some things the engine needs to cycle a certain amount of times. Which means it gets to and stays at normal operating temp for a certain amount of time(I think). If you properly foxed the problem then it should go away within a week or so. I would wait it off a little. I'm sure someone will chime in here to give you a definite answer

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post #3 of 22 (permalink) Old 02-26-2014, 12:38 AM
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Quote:
Originally Posted by josh52996 View Post
Hey guys my check engine light recently went off for an emissions code and i replaced both of the parts that could have been causing the problem. After replacing them i disconnected the battery which i was told would reset it but, the light is still on and won't turn off. Any ideas? I was told i might need to take it to a dealer to get a master resets but before i do that i want to see if there was anything else i could try.
Thanks guys!
No need to take it to a dealer, any decent scan tool can clear the code. Also if you take your car to parts store, they can read and clear the code for you. If the parts you changed didn't fix the problem it will come back once it senses the fault again. What did you replace, and what code was it?

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post #4 of 22 (permalink) Old 02-26-2014, 03:10 AM
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^^^Agree^^^

Need more details to offer added guidance...some codes are "historical" and others will remain until issue is corrected.

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post #5 of 22 (permalink) Old 02-26-2014, 05:58 AM
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any mods? what year and type of Cobalt?

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post #6 of 22 (permalink) Old 02-26-2014, 06:09 AM
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Ever thought that it might be a different code?

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post #7 of 22 (permalink) Old 02-27-2014, 04:42 AM
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Ever thought that it might be a different code?
BankerBalt is correct. Not at all times does replacing a sensor and clearing codes will correct the issue. We have a few guys at our Ford shop who are considered "parts hangers". Sometimes by replacing the part/sensor may cause a chain reaction to other sensors. I have seen it a few times at work and its very troubling to tell a customer that and see their face get really mad. You may have triggered another code from replacing a sensor or that may have not fixed the issue. You have to understand that a code coming from the PCM doesn't always means "replace sensor". It could also mean open/short/high resistance to the sensor itself. Remember, your dealing with a computer based engine monitoring system and it has certain values that it needs to use in order to clear the code. Any interruption during 2 drive cycles will trigger the CEL to illuminate.
Clearing the code from your scan tool will not all the time fix it. It also may have to cycle through a few drive cycles in order to respond. Some cars require half tank gas, evap canister full, minimum of 40 miles driven per cycle, speeds of 45/65 mph required, just based on manufacturer too.

Here is a very helpful tip on PCM systems: It requires a signal input from sensor (sensor is an input to PCM), then gets calculated through PCM, then sends an output signal (output signal such as a valve, solenoid, actuator) and keeps this cycle going during your drive cycle. If ANY of this is not reading correctly during a minimum of 2 drive cycles, a CEL will illuminate (OBDII standard).

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post #8 of 22 (permalink) Old 03-07-2014, 11:16 AM Thread Starter
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Hey guys its an 07 cobalt lt and the code was a p0449. I replaced both of the parts it said were faulty and then had the code read again about a week later when it wouldn't turn off and the same code was showing.
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post #9 of 22 (permalink) Old 03-07-2014, 02:19 PM
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Same problem with me! Just replaced my canister vent valve solenoid and the purge solenoid along with my gas cap. Still getting the p0449 code. Where are you in ohio josh? I'm in mentor
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post #10 of 22 (permalink) Old 03-07-2014, 02:27 PM
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Same problem with me! Just replaced my canister vent valve solenoid and the purge solenoid along with my gas cap. Still getting the p0449 code. Where are you in ohio josh? I'm in mentor
Probably changed the wrong parts, P0449 is gas pressure sensor.

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