I have 75,000 miles on my '97 4.6. Just got true dual exhaust installed; sounds great and actually have some power spunk. (2 chamber Flowmasters) The guy at the muffler shop said the O2 sensors should be replaced every 60-80,000 miles. This truck has four of them at a cost of $60-$80. Also just found out if has four cats. He said bad O2 sensors can ruin the cats; which will cost around $600+ each to replace.
In all my years of car ownership, I have NEVER replace an O2 sensor or a cat. Any of you guys replace your O2 sensors at a regular interval? Ever had one go bad or have to replace a bad cat? Replacing all the O2 sensors sure would be cheaper than cats; but how much trouble do they give?

Thanks!!!

 

whoever told you that the cats are around 600 dollars each is indeed correct--theyre insane to replace. O2 sensors should not be that expensive nor a big deal to replace. Since there are 4 of them, Id expect to pay a little bit of money, but IMO, they look easier to change than the spark plugs. They go bad sometimes, even at lower 60-80k milage.

 

I just replaced my 2 upstream O2 sensors with Bosch ones I bought from Murrays for ~ $45 each. One of mine got lazy(I used a scanner) at 27K. If you have that many miles on it, it seems a pretty safe bet that they could stand to be replaced.

 

Yeah, mine has about 136,000 miles on them, and they've been shot for about 30,000. You can get the high-flow magnaflow cats off eBay for way way WAY cheaper than the stock replacements, that is the route that you should go, just for price alone. I would start with the sensors by just replacing the front ones first. I mean, it's eventually going to need rear ones, too, but you may save money by just changing the first ones before you do them all.

 

What do you look for on a scanner to pickup a bad O2 sensor? I have a scanner but I dont' know what indicates the readings are bad. They are still working at 146,000 but I'm betting their getting old. How can I determine how many I should replace?

thanks.

jtdwab

 

cjmf150

The guy at the muffler shop is right about changing the O2 sensors every 60,000 to 80,000 miles. It is a wear and tear item that will degrade your performance over time. You don't have to replace all 4 O2 sensors. You only need to replace the 2 upstream O2's, which is the O2 sensor that is closest to the engine on each side of the motor. The 2 downstream O2's are there just to check for catalytic covnerter presence & function.