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Old 11-16-2012, 09:56 AM
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QSilver7 QSilver7 is offline
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Location: Northeast Indiana
 
Join Date: Aug 2008
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Mein Auto: 1997 740iL / 2006 X5 4.4
Quote:
Originally Posted by H2O View Post
Qsilver7...can you please summarize what you sent

... when i placed my car on my friend scanner it showed an error code 76 which is the oxygen sensor but the check engine since is not on, i thought that the engine light is not working but i tried test number 02 and it showed me that the light is working
The CEL/SES light only illuminates when a sensor registers or senses a fault TWICE (or 2 times or more). If you plug in a scanner and see a code listed...but the light in the instrument cluster hasn't illuminated...it means that the sensor only experienced the fault once. And... if you add to the scenario like another over-arching issue such as a failing alternator/battery/charging system...the sensor that registered the fault could be a false reading (especially if it only occurred once) due to low voltage from the cars electrical system.

If a problem is detected and then re-detected during a later drive cycle more than one time, the OBD II system must also illuminate the Check Engine Light (Service Engine Soon light) in the instrument cluster to alert the driver that a malfunction has occurred.


In your case...before throwing money at a new 02 sensor...determine if the issue isn't a sensor throwing a false code due to low voltage etc. Again, you only knew about the 02 code by hooking up a scanner and seeing that a sensor had registered a code. Plus we can determine that "the fault" only occurred once since the CEL/SES light never illuminated. Then you add the fact that you were also experiencing an electrical issue (which could be the real culprit)...perhaps causing a false code from the OBD II system.
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2006 E53 X5 4.4i (Sterling Gray) 12/05 mfg date <<~>> 97 740iL (Arctic Silver) 3/97 mfg date
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Last edited by QSilver7; 11-16-2012 at 10:04 AM.
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