P2270 Downstream O2 - Chevy Cobalt Forum / Cobalt Reviews / Cobalt SS / Cobalt Parts
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post #1 of 2 (permalink) Old 09-24-2016, 03:51 AM Thread Starter
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P2270 Downstream O2

Good morning everyone!

The check engine light came on in my Cobalt for the first time since I've owned it (3 years), and after pulling the code it's a p2270.

From what I've researched that secondary o2 sensor is only there to check for catalytic converter function. Is that true? If so, I'm thinking I'll probably leave it be for a bit - at least until I get home to the parents and have somewhere I can change it out (apartment living).

Appreciate any insight, thanks.
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post #2 of 2 (permalink) Old 09-24-2016, 06:26 AM
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It's there to measure catalytic efficiency yes, but is also used to trim fuel mixture. If you find your Cobalt to be a bit harder on fuel you will know why. If it's only the heater part that burnt, the HOČ will still work but vehicle will take longer to go into closed loop.

In your case engine will never go into closed loop because it is the sensor itself that is faulty.

P2270: HO2S Signal Stuck Lean Sensor 2

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Last edited by Coby7; 09-24-2016 at 06:29 AM.
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