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Reprogram the Computer to Fix Knock Sensor Issue?

jdaniel83

By jdaniel83
in Ask A GM Technician

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jdaniel83 Enthusiast

jdaniel83

Posted
Posted

I was told by a friend who works for a local auto repair shop that I could have my PCM flashed or reprogrammed so that the knock sensor issue wouldn't cause the computer to retard the timing and cause the poor performance/MPGs that it has been doing. Is this true and if so do I have to take it to the dealer to get this done?

 

Oh and a short version of my knock sensor issue is I went to replace my sensors and harness and the rear sensor's threads appear to be stripped cause I can't get it out. It won't loosen or tighten so I just left it in there despite it not being completely tight. So now I'm getting the Bank 2 Sensor Low Input code. Can the computer be reflashed or reprogrammed so that it won't recognize that sensor?

 

The truck is an '01 Z71 with the 5.3L motor.

TJay74 Senior Enthusiast

TJay74

Posted
Posted

Cant reprogram the knock sensor like your friend is suggestiong without using HP Tuners or EFI Live. While you can tune out the error code for the knock sensor with those programs it would be better to fix the knock sensor correctly. I belive that the knock sensors holes are blind so they should be easy to fix once you get them out.

 

Try spraying some penetrant down in the holes for a bit to break the threads free.

jdaniel83 Enthusiast

jdaniel83

Posted
  • Author
Posted

Thanks for the response and info. I'll try spraying some PB Blaster down in there and see if that helps to get the sensor out. In case I can't get it out would a place that does custom PCMs like Blackbear be able to tune out the error code?

TJay74 Senior Enthusiast

TJay74

Posted
Posted

I would think so, but I would do everything else before I came to that point including replacing the valley pan first. Tuning out the knock sensor is bad, couple that with having some bad gas, really hot day and you being hard on the throttle and you are only asking to get some detonation that is not controlled which can lead to serious damage to your pistons.

 

The worst we ever did was reduce sensitivity, but never tuned the sensors out completely.

txab Senior Enthusiast

txab

Posted
Posted

Get the sensor replaced. Quit trying to half ass it. You need the knock sensors to be operating

jdaniel83 Enthusiast

jdaniel83

Posted
  • Author
Posted

Thanks for the responses, I'm not trying to half ass it I'm just exploring all my options if it comes to reprogramming it as a last resort. I've tried getting the valley pan plate off but it won't come out unless I get the sensor out so hopefully I can get it out this weekend after Thanksgiving.

 

The strange part is that the truck is running fine, as good if not better than it did before the original sensor issue started. None of the valve clattering or lack of power that I was experiencing before, and the mileage is back to what it was also. Just thought it was kinda weird.

  • 3 months later...
ZimHunter New Member

ZimHunter

Posted
Posted

I also have a knock sensor code appearing, #2 bank. The truck is a 2002 Z71, 5.3, 3.73 gears with 210K on the clock. No knock, runs great with lots of power, 16mpg in town driving. I do drive it like a little old lady. Can I expect the truck to run any better with replacing the sensors? Thanks

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