GIlly,

Interestingly, when I started the vehicle this morning the check engine light came on; this is after I cleared it by disconnecting the battery yesterday. Then while driving but before I got over to my buddy's shop the check engine light when out.


I had a buddy hook my vehicle to an Ottoscan OBD2 reader. The Ottoscan shows live data. He compared the graphs for each bank. While I did not understand all the numbers and graphs he said the problem was the sensor, i.e., the one behind the CAT on the drivers side, I think he said it's about worn out and that the voltage variation between the O2 sensor before the CAT and the sensor after the CAT did not vary to such a degree as to indicate that the CAT is failing

He said the problem is not with the CAT, but with the sensor after the CAT as indicated by P0156 code.

He said as other have too, that the sensor behind the CAT only measures emissions and does not affect performance. Since my CAT is functioning fine there is no reason to replace the sensor other than the light going on.

At the present time vehicles do not have telemetric links to big brother telling him or her as the case may be that my vehicle may be emitting exhaust gases not in compliance with whatever the current law mandates. So with that in mind I guess, at least for now I'm safe.

Dutch,

I don't know which Optima you are using but I've found them to be poor performer for cars that are not driven very often. I had so much trouble with mine not staying charged that the company sent me a brand new one. I've not used it though since I've found that the Odyssey batteries are better. While they both use the same technology, I've found the Odyssey will charge to a higher voltage and hold it longer.

I used brand new batteries of each brand. I charged them for 5 hours with a Guest 3 stage charger. I measured the voltage 1 hour later, Optima 13.07 volts and Odyssey 13.18 volts. Neither battery has ever been connected to a load.

Results
7 days later: Odyssey--12.92 Optima--12.69

14 days later: Odyssey--12.81 Optima--12.67

50 days later: Odyssey--12.81 Optima--12.63


This difference may not seem significant but the state charge of a battery that is 12.8 volts is 100% and the state of charge of a battery with about 12.60 volts is only 80%.