# Check engine light codes

**URL:** <https://community.cartalk.com/t/check-engine-light-codes/15463>\
**Category:** Maintenance/Repairs\
**Created:** [June 17, 2008, 10:54am UTC](https://community.cartalk.com/t/check-engine-light-codes/15463 "2008-06-17T10:54:41Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![raycyrx](https://avatars.discourse-cdn.com/v4/letter/r/f07891/32.png) [@raycyrx](https://community.cartalk.com/u/raycyrx)\
**Post date:** [June 17, 2008, 10:54am UTC](https://community.cartalk.com/t/check-engine-light-codes/15463/1 "2008-06-17T10:54:41Z")

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My service engine soon light came on recently, and my father in law used his code reader to read it. It had two errors:  
  
 High voltage O2 sensor bank 1 sensor 2  
  
 High voltage O2 sensor bank 2 sensor 2  
  
  
  
 Now, how do I find out WHICH sensors for my vehicle need to be replaced?

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**Author:** ![BustedKnuckles](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/bustedknuckles/32/25_2.png) [@BustedKnuckles](https://community.cartalk.com/u/BustedKnuckles)\
**Post date:** [June 17, 2008, 11:12am UTC](https://community.cartalk.com/t/check-engine-light-codes/15463/2 "2008-06-17T11:12:25Z")

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Be careful. The code is a circuit problem to the sensors, maybe not the sensors themselves. The circuit needs to be evaluated before just plopping down money on sensors.

Sensor 2 is the rear sensor. This sensor is for emissions checking only, and monitors the catalytic converter efficiency. I forget which bank is left or right, but, since the codes call for both, then it is both sides. This problem will not affect the engine. This is simply an emissions check.

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**Author:** ![hellokit](https://avatars.discourse-cdn.com/v4/letter/h/6a8cbe/32.png) [@hellokit](https://community.cartalk.com/u/hellokit)\
**Post date:** [June 17, 2008, 12:38pm UTC](https://community.cartalk.com/t/check-engine-light-codes/15463/3 "2008-06-17T12:38:42Z")

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There may be nothing wrong with either oxygen sensor! In normal operation, when the catalytic converter is doing its thing, the rear oxygen sensor will have a lower voltage than the front. If nothing is happening in the catalytic converter (if it’s not converting) front and rear oxygen sensors will have the same voltage output.  
There may be a problem in the engine 'way before the oxygen sensors and catalytic converters.  
You can get the DTC code troubleshooting chart from [www.alldata.com](http://www.alldata.com) Your public may have an online subscription (free to you) through there website Reference section.  
You could be money ahead if you took it to a mechanic for diagnosis. You could make the deal with him, that: he diagnose, you change parts, if any.

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**Author:** ![nbpt100](https://avatars.discourse-cdn.com/v4/letter/n/9f8e36/32.png) [@nbpt100](https://community.cartalk.com/u/nbpt100)\
**Post date:** [June 28, 2008, 2:09am UTC](https://community.cartalk.com/t/check-engine-light-codes/15463/4 "2008-06-28T02:09:56Z")

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Bank 1 is the side of number 1 cylinder. Bank 2 by default is the other bank.

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**Author:** ![crankwalk5](https://avatars.discourse-cdn.com/v4/letter/c/3e96dc/32.png) [@crankwalk5](https://community.cartalk.com/u/crankwalk5)\
**Post date:** [June 28, 2008, 2:37am UTC](https://community.cartalk.com/t/check-engine-light-codes/15463/5 "2008-06-28T02:37:16Z")

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short to 12v.,or an open circuit.

good luck.