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Discussion Starter · #1 ·
Hey, I sourced a check engine light a while back that indicated one of my o2 sensors needs replacing. My wife bought me a code reader for christmas so I tried it out in the truck and says no codes found? I thought a trouble code stayed in the pcm memory until you erase the code? I was working on the truck and disconnected the battery, would that have erased the code?
 

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Disconecting the batter doesn't erase a code. Those are written to memory and stay till cleared.

Did you get the O2 fixed by someone? If so it's possible they cleared the code. If not than it's possible that your code reader isn't working correctly and it's not really reading. The only way I can think of that you will know for sure is to take it to someone that reads codes everyday and have them check it. Most places like Advance Auto have code readers and will most of the time do it for free, I'm sure a dealer will charge you. If they see the code then your code reader isn't working correctly If they don't see a code in memory and it wasn't cleared when it was repaired then I have no clue.
 

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if you disconnect ed battery before you scaned the computer. You erased the code, if the problem with the o2 is speratic the computer might not pick it back up. The computer will ignore small or speratic issues for so many start cycles before it will set a code. Only a complete failure of lack of signal will set a code right away after disconnecting battery.
 

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Discussion Starter · #6 ·
if you disconnect ed battery before you scaned the computer. You erased the code, if the problem with the o2 is speratic the computer might not pick it back up. The computer will ignore small or speratic issues for so many start cycles before it will set a code. Only a complete failure of lack of signal will set a code right away after disconnecting battery.
Yes, sorry I forgot to mention that this has been a speratic problem. I originally found out it was the o2 sensor by turning the ignition on/off about 3x and the trouble code was indicated on the odometer. I just wanted to double check it with my new Christmas present. Thanks guys I'll keep you posted.
 

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if the problem happens and the cel is turned on..then the code will be saved and stored...u need an actual scan tool to look at saved codes...that code will be there even after the cel is turned off...had this same problem with my ram...was told that a faulty connection to the obd "socket" or plug could cause the cel to stay on.
 
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