2010 aveo5 LT still runs rough after changing valve cover gasket.

I changed the front o2 sensor but not the rear. The code stayed off for a few hundred miles but now it's back. I haven't checked the code yet but i'm assuming it's the same. I guess I'll change the rear o2 sensor. The o2 sensors looked fine. They weren't particularly caked up but the car does have 100k on it so to me they looked like used o2 sensors.

For the front o2 sensor amazon was $20 cheaper than rockauto for the same brand, Acdelco.

It's my wife's car so I'll have to ask her if her fuel mileage improved. I would expect it to with a new front o2 sensor.

You haven't looked at the most obvious which is a compression check. I don't see how many miles/km you've logged either. Could be you're wasting time and money on the O2 sensors without checking what's happening with the middle two cylinders.

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Originally Posted by shipwreck17

We don't have inspection either but the problem started at the same time as the oil leak plus we're not getting the MPG we used to. I'm going to replace the upstream o2 sensor. From what I read trying to clean an o2 sensor isn't worth the time. I found it for $80 on amazon.

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Check Rockauto.com .

Just for grins , check the PCV valve / system .

Best of luck , :-)
Wyr
God bless

Compression check and pcv valve are both good ideas.

Update: The car still has a CE light. I haven't done anymore work on it recently, got tied up with other projects. It runs fine and MPG is back to normal so currently the only symptom we have is the CE light for the Cat. I'll do some more investigating soon. This year it seems I'm 50/50 on amazon vs rockauto for the cheapest parts. Anymore those are really the only two places I check unless I need something immediately.