# 99 Grand Am 3.4L Knock Sensor Issue.

**URL:** <https://forums.speedlife.net/t/99-grand-am-3-4l-knock-sensor-issue/209915>\
**Category:** NYSpeed Automotive\
**Created:** [March 9, 2011, 11:30am UTC](https://forums.speedlife.net/t/99-grand-am-3-4l-knock-sensor-issue/209915 "2011-03-09T11:30:24Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Justin](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/justin/32/7459_2.png) [@Justin](https://forums.speedlife.net/u/Justin)\
**Post date:** [March 9, 2011, 11:30am UTC](https://forums.speedlife.net/t/99-grand-am-3-4l-knock-sensor-issue/209915/1 "2011-03-09T11:30:24Z")

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OK, this one has me stumped. I picked up a 1999 Grand Am (My first mistake I know) It had a check engine light for the knock sensor (Low Voltage). I figure a quick change of the knock sensor and all would be well.  
First thing I did was swap the sensor for a new one and clear the codes, next day the light came back on.  
Next I used a multi-meter and tested the sensor and it test out as good, I figure there must be a break in the line somewhere so I replaced the line from the knock sensor to the PCM. I cleared the light, came back the next day.  
I then did some research and found that the knock sensor output on the PCM could be bad, I replaced the PCM. Now the check engine light is back.

Now that I have a new PCM, New Sensor, and a New Wire I am stumped. Any ideas?

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**Author:** ![Mankthetank19](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/mankthetank19/32/5295_2.png) [@Mankthetank19](https://forums.speedlife.net/u/Mankthetank19)\
**Post date:** [March 9, 2011, 8:30pm UTC](https://forums.speedlife.net/t/99-grand-am-3-4l-knock-sensor-issue/209915/2 "2011-03-09T20:30:07Z")

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You should check out [www.gaownersclub.com](http://www.gaownersclub.com) for all the info you need on the 3400

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**Author:** ![ubengineering](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/ubengineering/32/5171_2.png) [@ubengineering](https://forums.speedlife.net/u/ubengineering)\
**Post date:** [March 10, 2011, 7:42am UTC](https://forums.speedlife.net/t/99-grand-am-3-4l-knock-sensor-issue/209915/3 "2011-03-10T07:42:46Z")

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idk how it for grand ams but for my neon, the knock sensor was dependent on how it was torqued down