CA Smog Test Question Re: HC

[jim_hoyland]

It's a '98 with 60K miles. It has been suggested that o2 sonsor(s) cold be at the heart of the problem.

The most interesting thing I've noticed is the similarity of results after two years.

[Topless]

Originally Posted by jim_hoyland

It's a '98 with 60K miles. It has been suggested that o2 sonsor(s) cold be at the heart of the problem.

The most interesting thing I've noticed is the similarity of results after two years.

Aging O2 sensors will throw a very specific error code and CEL so they are possible but less likely. Aging cats, MAF, or leaky injectors are more likely. With a Durametric scan you can get a closer look at fuel mixture trims and cat efficiency which might narrow down the problem. If the car is trimmed nearly full lean but still running rich it points to a bad MAF or injectors.