Weird engine noise, bad MPG - Chevy Cobalt Forum / Cobalt Reviews / Cobalt SS / Cobalt Parts
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post #1 of 3 (permalink) Old 12-17-2018, 02:04 PM Thread Starter
Join Date: Dec 2018
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Getting about 20mpg, have this strange clicking noise when i accelerate. What do you guys think it is?

Engine codes
bank 1 o2 sensor
knock sensor [intermittent]

Video below,

Last edited by 2006chevycobalt; 12-17-2018 at 02:09 PM.
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post #2 of 3 (permalink) Old 12-17-2018, 02:19 PM
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Location: Magnetic Hill, New-Brunswick
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Sounds like your flex pipe has sprung a leak which is probably the reason for the HOČ code. Second HOČ isn't seeing all of the exhaust that is going by the first HOČ because of the leak. You may also have a broken exhaust shield, I seem to be hearing that in the background. Any Mom and dad shop should be able to weld in a new flex pipe fairly cheap and pull that broken shield out completely or re-weld it in place.

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post #3 of 3 (permalink) Old 12-18-2018, 07:38 AM Thread Starter
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I checked the flex pipe i cant find a leak, maybe the cat is clogged? The ticking noise sounds like its comming from the bottom of engine next to the timing chain, i already replaced the tensioner. Car has 140k miles. Im thinking about cutting out the two cylinders behind the flex. If it has a knock sensor can it be the rod? Its strange that it only does it when it warms up. I might try to sea foam it tonight.
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