andynoel78

Hi all:

About month ago, the CHECK ENGINE, VSC, and VSC OFF lights came on in the dash of my '03 SC430 (~175k miles). Took it to the dealer and they read the codes; indicating a bad O2 sensor. They replaced it, and the lights went off. A few days later, the lights came back on. The lights remained ON until this past weekend.

On Sunday, i went to start the car in the morning and the thing wouldn't turn over. Turns out the battery was dead. The label indicated it was 5yrs old. So i bought a new battery. After installation, i noticed the error lights were no longer illuminated on the dash, but just figured it was due to the fact that the battery was disconnected during installation. But after driving it extensively since then, the lights have remained off.

Something else i've noticed since installing the new battery is the lack of the "rotten egg" smell from the exhaust. Before the change, i noticed a significant decrease in acceleration and the emissions smelled very bad. But for the past few days, i've noticed a dramatic increase in power and cleaner smelling emissions. Not sure if they're related...

Could the check engine lights have been the result of my battery dying? I'm not sure why they haven't come back on since the battery replacement. Nor a reason why i'm noticing improved performance and better smelling emissions.

Thanks for the input!

bb430

iTrader: (1)

I don't think the battery has anything to do with CE light, but your new O2 sensors may very well contributed to the less odor as well as better combustion for better and more efficient engine running. Some codes will be stored in the memory so you may still want to have codes read to make sure they are gone for good.

LexBrett

It's my understanding that the pre-cat O2 sensors play an important role in optimizing engine parameters such as air fuel ratios and emissions. So it makes sense if your car would get better mpg, HP, and lower emissions if you replace your bad sensors. I have just never heard if such a drastic case. In one book I read it even suggested to change pre-cat O2 sensors before they fail to maximize power and mpg. Others on CL have suggested they either work or they don't and there is no need to change them unless they fail. Either way, it looks like you solved your problem by replacing the sensors.

The battery on our car is very prone to failure, as you can research by looking at threads on this forum. Many if us even run a battery tender to periodically "top off" the battery. I also have an aftermarket voltmeter wired to my battery to keep an eye on it..