Q45 Y33 2000 O2 Sensor Observation in regards to CEL

[willko1]

Ok so I replaced both rear heated O2 sensors 5000K miles ago with Bosch broad range units and I have noticed something very interesting in regards to CEL. I no longer get any check engine lights, primarily the ones I was getting were with codes for knock senor and egr related, but I also had a few other strange ones pop up but code free sice the install ...weird, I am surprised to say the least. Not sure if this may help others.

[ddsmith60]

Hey wilko,
I replaced my rear heated O2 sensors on my Q45 because they were throwing the codes for lack of activity. With the Torque Pro program on my HTC Droid phone and the Bluetooth Dongle I was able to see the voltage signal wasn't moving much before changing the sensors. Following the change to the new sensors, they started reacting properly and cleared the O2 sensor code but unfortunately it did set the code for bank 1 converter efficiency. I must say that I was able to figure out this code was going to set, before it ever did, from monitoring the O2 sensor voltage trends. Now I pretty much understand what the O2 sensor codes are telling me. I'm going to replace the catalytic converter on the drivers side to fix the problem and I will monitor the performance of the cat using this program. It is an aftermarket cat.

[willko1]

Hey wilko,
I replaced my rear heated O2 sensors on my Q45 because they were throwing the codes for lack of activity. With the Torque Pro program on my HTC Droid phone and the Bluetooth Dongle I was able to see the voltage signal wasn't moving much before changing the sensors. Following the change to the new sensors, they started reacting properly and cleared the O2 sensor code but unfortunately it did set the code for bank 1 converter efficiency. I must say that I was able to figure out this code was going to set, before it ever did, from monitoring the O2 sensor voltage trends. Now I pretty much understand what the O2 sensor codes are telling me. I'm going to replace the catalytic converter on the drivers side to fix the problem and I will monitor the performance of the cat using this program. It is an aftermarket cat.

Wow you are beyond me with the tech, blue tooth, droid etc. It is my wife's daily so no codes is good but would like to be able to diagnose it better when it has to many miles and I can play with it. could you link the info on the devices that you use as I only have a OBD II reader that gives me limited data. Also do you know if it is ok to remove the cats or punch them out and remove the rear heated sensor or would that throw the ECM into a meltdown? I met a person the other day that put on straight pipes on a 98 and said he didn't have rear o2, think its BS though. Thanks for the info in advance, BEST Will K

[ddsmith60]

Check my post from Nov 1st on information about the program and bluetooth dongle. As for the removal of cats, it will definitely set the Check Engine light because the rear O2 sensor will be seen as failed if it is removed or if you leave it there it will figure out the cat is bad or not there. The car will run fine without the cats but you will have to find a way to trick the ECM into thinking the rear O2 sensor is there and is getting an expected signal.