Hello,
I've lurked on here for quite some time, using old threads to help troubleshoot and maintain my vehicle. Let me say thank you in advance for reading this post and for all of the knowledge and information that has been compiled here throughout the years. I am sorry for the length of this post, but I am trying to provide as much information about the current situation in hopes for a better understanding.
I have run into several problems on my automatic 2009 Aveo within the last year. I couldn't rid myself of codes 0141, 0140, 0138, 0036, 0053, and 0054. I installed a new Bosch upstream o2 sensor, then a NTK. I also installed a new NTK downstream o2 sensor, followed by a much cheaper Kwiksen brand sensor. All of the cel oxygen sensor related codes persisted. During this time I also installed new AC Delco spark plugs and found several holes in the mass airflow ducts. I unplugged the mass airflow sensor during this time and several mas related codes showed up. I plugged it back in, cleared the codes and thoroughly duct taped the holes after researching a replacement and finding that the whole OE system had be to bought. There was a small amount of oil pooled in one of the plug wells, but tightening up the head gasket appears to have taken care of that.
Previous to these repairs I had only replaced the coil pack after the "hold" light came on one night when driving home two years ago.
After checking to make sure there were no apparent shorts or breaks in the wires from the o2 sensors I tested the connectors with a digital multimeter. There were no problems with my findings.
At this point I took the vehicle to a local repair shop to get it diagnosed. I had an NTK o2 sensor in the upstream and the Kwiksen o2 sensor in the downstream. After several days they contacted me saying they were 99% sure that the ECU had to be replaced. According to them that would take care of all the codes that were present. It took them almost a week to replace the ECU. They had problems with the programming and only told me that they had to install an update to finally get to take. I don't know if the update was hardware or software related.
After the ECU was installed and programmed they told me that the downstream o2 sensor wasn't acting properly. I wasn't exactly surprised because the Kwiksen sensor was really cheap the connector fit seemed extremely tight. I agreed to have them replace it with an AC Delco downstream sensor.
I went to pick up the vehicle and they told me when they went to move it out of the bay that it threw a code for the upstream sensor. I brought them the original AC Delco sensor as well as the Bosch that I had purchased. They installed the original AC Delco sensor and the vehicle ran fine for a while then abruptly died and threw a code. They suggested installing a brand new AC Delco upstream sensor. I asked them about the Bosch that I had brought them and they hadn't even tried it. They installed it and the vehicle ran fine with no check engine lights.
While trying to complete the drive cycle so I could finally take the vehicle through emissions testing, the car threw an upstream o2 sensor code. I bought a brand new AC Delco upstream o2 sensor, installed it, and reset the cel. I drove around town for a while with no problems. The next day as I am sitting in the emissions testing line the cel comes on. I took it right back to the shop and after 2 days they called me and left a message with the info that it is p-0420 and related the the catalytic converter. They are going to try and charge me for another diagnosis now.
I really have no idea what to do now. I didn't have a chance to return their call before they closed for the day. I don't completely understand why only the OE o2 sensors will work in my vehicle. I really need to get this sorted out so I can get my tags renewed. Based on research it looks like the problem could be related still to the air / oxygen ratio or the sensors relaying info that is too similar? The only physical problem I have noticed is the vehicle running slightly rougher when the ac is turned on. I was planning on adding some freon after I got the tags renewed.
Any help would be greatly appreciated because at this point I am really at a loss.
Thanks in advance,
Donovan