Chevy & GMC Vans

On the older Astros I've had the OX sensor AFTER the cat conv just turned on the light to let you it was failing. It seems that on my '04 Cargo it is also a part of the engine management. I thought the van had gotten kind of sluggish and the mileage went in the dumpster. Everything on the scanner looked within spec except the timing was -6 @ idle and +24 @ higher revs. Tech shut off the SES light saying it wouldn't stay off for long and the engine freed right up and the HP, such as it is, is back. Still probably need to replace the cat but it was interesting to see that the down stream sensor has an effect on the engine these days.

Yeah they do! My truck was acting up, loss of power, hesitation, blowing black smoke yet the SES light never came on. Hooked a scanner up and found the after-cat O2 sensor was not working. It was reading right at 0 volts basically with little change. New sensor and it's great again!

I have a P420 code on the OBDII and haven't done anything about it yet. I'm not certain if it's the OX or the CAT. I've asked around, searched the forum and stories are mixed.

Where do I spend my money?

Sensor probably a lot cheaper that the cat, or whole header pipe with the two cats in it if you have a late model.

OX is $70 (x3)
welded-in cat is about $150
bolted-in cat about $300

It's awesome; you're from Janesville!

1401 Barham my entire life.

A very good friend of mine is from Jefferson, met him in the USAF 25 years ago. We're still great friends. And I'm a huge fan of the BoDeans!