A couple of months ago I came to own a 2005 Chevy Cobalt 2.2L auto trans 180K miles on it from a friend of mine who did a repo on it. When I got it, the check engine light was on, and found some print outs from Auto Zone in the car that indicated upstream O2 sensor heater was bad and random misfires. But the car ran OK, but the MPG seemed low (I was getting 21 MPG, mostly city type driving)
Codes I found from the printouts in the car were: P0300, P0135
Car ran good for 2 months, but once or twice it died at a stop sign, and would restart no problem, but be rough in drive for a mile or two then clear up. A few days ago, same thing, but it wouldn't go over 20 MPH even with my foot to the floor and was running totally rough and would die any time I came to a full stop with it in drive. I was able to limp it to work after an hour of stop and pull over to let traffic pass and try and get it down the road again. Figured the o2 sensor had failed hard finally.
Replaced the upstream o2 sensor and all 4 plugs. MPG went up by 5 MPG after that, so took it to auto zone and had them read/clear the check engine light.
I got about 1 mile away from Auto Zone and the car totally bogged down again, and I had to just about had to floor it to keep the car going even 20 MPH. If I had it in park or neutral, it would stay running, but even at idle speed it was loping, but if I put it in drive, it would die, unless I was flooring the gas pedal, and it ran so rough it was barely able to stay running.
No check engine light when it was acting up. Got to a good place to stop, went in had dinner, come back out an hour later, and it is purring like a kitten and then the check engine light came on again.
Had the codes read today and we got:
P0842: transmission fluid pressure sensor circuit low voltage
P0974: shift solenoid (SS) control circuit high voltage
P0700: Tranny control module (TCM) requested MIL illumination [seems like this one happens anytime a tranny problem is detected - the TCM gets a problem code from some other sensor and then asks for the check engine light to come on]
P0420: Catalyst system efficiency below threshold
The previous codes that cleared and didn't come back after replacing the o2 sensor and plugs were:
P0131 - o2 sensor circuit, low volts (sensor 1)
P0132 - o2 sensor circuit, high volts (sensor 1)
P0134 - sensor circuit - no activity detected (sensor 1)
P0135 - o2 sensor heater circuit malfunction (sensor 1)
P0300 - random/multiple cylinder misfire detected
I don't trust the catalytic convertor code, since they way it was running it it acted up and how much I had to stomp on the gas pedal to just get it to a spot I could park it, I figure pure gas was going down the exhaust pipe. I might be wrong, but if it was the catalytic converter, wouldn't I have problems all the time?
Any help will be very much appreciated!
Thank you.
And let me know if I need to supply more information.
[edit - and i may have posted this in the wrong section of this forum - sorry!]
Codes I found from the printouts in the car were: P0300, P0135
Car ran good for 2 months, but once or twice it died at a stop sign, and would restart no problem, but be rough in drive for a mile or two then clear up. A few days ago, same thing, but it wouldn't go over 20 MPH even with my foot to the floor and was running totally rough and would die any time I came to a full stop with it in drive. I was able to limp it to work after an hour of stop and pull over to let traffic pass and try and get it down the road again. Figured the o2 sensor had failed hard finally.
Replaced the upstream o2 sensor and all 4 plugs. MPG went up by 5 MPG after that, so took it to auto zone and had them read/clear the check engine light.
I got about 1 mile away from Auto Zone and the car totally bogged down again, and I had to just about had to floor it to keep the car going even 20 MPH. If I had it in park or neutral, it would stay running, but even at idle speed it was loping, but if I put it in drive, it would die, unless I was flooring the gas pedal, and it ran so rough it was barely able to stay running.
No check engine light when it was acting up. Got to a good place to stop, went in had dinner, come back out an hour later, and it is purring like a kitten and then the check engine light came on again.
Had the codes read today and we got:
P0842: transmission fluid pressure sensor circuit low voltage
P0974: shift solenoid (SS) control circuit high voltage
P0700: Tranny control module (TCM) requested MIL illumination [seems like this one happens anytime a tranny problem is detected - the TCM gets a problem code from some other sensor and then asks for the check engine light to come on]
P0420: Catalyst system efficiency below threshold
The previous codes that cleared and didn't come back after replacing the o2 sensor and plugs were:
P0131 - o2 sensor circuit, low volts (sensor 1)
P0132 - o2 sensor circuit, high volts (sensor 1)
P0134 - sensor circuit - no activity detected (sensor 1)
P0135 - o2 sensor heater circuit malfunction (sensor 1)
P0300 - random/multiple cylinder misfire detected
I don't trust the catalytic convertor code, since they way it was running it it acted up and how much I had to stomp on the gas pedal to just get it to a spot I could park it, I figure pure gas was going down the exhaust pipe. I might be wrong, but if it was the catalytic converter, wouldn't I have problems all the time?
Any help will be very much appreciated!
Thank you.
And let me know if I need to supply more information.
[edit - and i may have posted this in the wrong section of this forum - sorry!]
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