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Discussion Starter #1
I just bought this about four days ago and I knew it needed a few things. Here are the codes it's throwing. If anyone has any advice or has had any of these please let me know. This is my first Cobalt and hope that it turns out to be a good car. Also, does anyone know where I would post for wanted parts? (dumd question I know)

P0053- (O2 Sensor) Heater
Explanation-the powertrain control module controls the electrical circuit for the oxegen sensor heater. The computer has recognized a failure in this curcuit.

P0496- EVAP flow during a non-purge condition
Explanation- The ECM has detected pressure in the EVAP system during a non-purge condition

P0442- EVAP small leak/no flow condition
Explanation- The evap emission system is monitored for it's ability to hold vacuum

P0128- Coolant Temp is always low
Explanation- The powertrain control module verifies that the engine is at a proper operating temp.
 

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OBDII reader would be nice to have

P0053- (O2 Sensor) Heater Explanation-the powertrain control module controls the electrical circuit for the oxegen sensor heater. The computer has recognized a failure in this curcuit. P0496- EVAP flow during a non-purge condition Explanation- The ECM has detected pressure in the EVAP system during a non-purge condition P0442- EVAP small leak/no flow condition Explanation- The evap emission system is monitored for it's ability to hold vacuum P0128- Coolant Temp is always low Explanation- The powertrain control module verifies that the engine is at a proper operating temp.[/QUOTE said:
I would clear codes and see which one comes back.

Check antifreeze and top up. Might have a bad thermostat or temp sensor.

0442 and 0496 can be that your gas cap was loose. Make sure the seal on cap is good. If these codes come back then you might have a fiiler neck leak or gas tank leak. (Do you smell gas?)

Last but not least which might be your only problem O2 sensor. If code comes back well check wires if they are good you might need a sensor.
 

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Ok, so I disconnected the battery and cleared the codes. It took about a week and the check eengine light came on again, this time It's only the P0496 and P0128 ( 2 of the original codes). When using the scan tool it gives three solutions per code. Should I follow them in order? Or just pick what I think should be replaced? Has anyone had these codes, if so let me know how you fixed them. Lastly I noticed my coolant temp wasn't registering the other day on my gauges, then my wife tried to turn on the AC and the compressor wouldn't kick on. Then today the temp was reading properly and I tried the AC and it worked. Chance? Or could it be related?
 

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If you leave key in ignition (engine not running) in running position (not accessories) long enough you will get some codes which make no sense. So make sure these codes came up while driving or at least while engine was running. 0496 is usually caused by bad purge solenoid or it's connector. 0128 caused by bad temp sensor or corrosion on contacts of such sensor.
Try the cheapest solution first, remove and inspect temperature sensor connector. Clean and apply dielectric grease and re-install. Wait for codes to re-appear. I would do the same for purge solenoid connector. Corroded connectors will usually act up with high humidity. As far as temperature gauge and A/C don't know why those would be related but I do know that if your radiator fan doesn't work your A/C won't either.
 

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Good Morning, Blackhawk,

Sorry to hear that you’re having these code concerns with a vehicle that you recently purchased. Was this from a dealership or from an independent vendor?

Have you found a solution since your last post?

If you would like to work with GM Customer Assistance towards getting these concerns resolved, or if you want for me to look into your vehicle’s warranty/recall information, please private message me your name and VIN.

Best,
Sarah
GM Customer Service
 

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Discussion Starter #6
Ok, so I picked up a new purge solenoid and temp sensor (AC Delco). I disconnected the battery and knocked out the purge valve but havent done the temp sensor as I didnt have the right size wrench. So far no codes however I've only driven it about a block or two so I'm sure the temp sensor will register again. The weird part is when the check engine light comes on I check the coolant temp and it says coolant-----*. When it says this I try the ac and it wont come on, however when the temp registers the ac comes on. Not sure how that's tied in but I'm assuming if the PCM doesnt know how hot/cold the car is running it won't allow the ac to come on. No sure, maybe that sounds dumb. Anyone had this issue or know what causes it?
 

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So I assume cleaning contacts didn't work. It is best to do these one at a time to see if you are doing progress by process of elimination.
 
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