I got the codes read, and I was told to Google the results, but no luck! I have PO128, PO300, and PO440. Thanks!
Jul 2, 2021 at 8:56 AM
What do these codes mean PO128, PO300, and PO440?
2001 BUICK LESABRE
JERRYKAUFFMAN
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Good evening,
The 128 is for the thermostat. It looks like it may be stuck open not allow the engine temperature to reach normal operating temperature. I would replace the thermostat.
https://www.2carpros.com/articles/how-an-engine-thermostat-works
https://www.2carpros.com/articles/replace-thermostat
The 300 is for a misfire. The most common cause is low fuel pressure from a bad fuel pump. I would check the actual pressure to be sure it is working correctly. I attached guides for you to follow as well. You can rent a tester at a parts store.
Fuel System Pressure
Key On Engine Off 53-59 PSI.
https://www.2carpros.com/articles/engine-misfires-or-runs-rough
https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator
https://www.2carpros.com/articles/how-to-replace-an-electric-fuel-pump
The 440 is for the canister vent valve in the emissions. It is stuck open causing a large leak. I posted the location and procedure below.
I attached the procedures below for you. of the fuel pump and thermostat.
Roy
The 128 is for the thermostat. It looks like it may be stuck open not allow the engine temperature to reach normal operating temperature. I would replace the thermostat.
https://www.2carpros.com/articles/how-an-engine-thermostat-works
https://www.2carpros.com/articles/replace-thermostat
The 300 is for a misfire. The most common cause is low fuel pressure from a bad fuel pump. I would check the actual pressure to be sure it is working correctly. I attached guides for you to follow as well. You can rent a tester at a parts store.
Fuel System Pressure
Key On Engine Off 53-59 PSI.
https://www.2carpros.com/articles/engine-misfires-or-runs-rough
https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator
https://www.2carpros.com/articles/how-to-replace-an-electric-fuel-pump
The 440 is for the canister vent valve in the emissions. It is stuck open causing a large leak. I posted the location and procedure below.
I attached the procedures below for you. of the fuel pump and thermostat.
Roy
Images (Click to enlarge)
Jul 2, 2021 at 3:38 PM
Thanks, Roy!! God bless you!
Jul 3, 2021 at 11:06 AM
You are welcome.
Always glad to help.
Roy
Always glad to help.
Roy
Jul 3, 2021 at 11:15 AM
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