HarryD

Hey guys -- I am of the school of thought that if an electronic sensor is going bad, it'll throw a code. I've learned the hard way that sometimes there's that fine threshold of lazy and bad where no code is thrown (coil packs, yay!).

But as far as o2 sensors, primary and secondary, is there a reason to replace them at 100k miles even if they're not throwing a code?

I have an AP1 2002, spa yellow, and I do burn oil and my rear bumper is always covered in soot. My chrome exhaust tips are almost always black 24-48 hours after washing. Safe to say my car runs rich. No other mods, all stock.

Thoughts? Expert opinions, will changing my o2 sensors make any difference, or a waste of money?

Thanks!

Sabre

I'm no expert, but it seems to me that if it's not throwing a code specific to the sensor failing, its "working" so there is no reason to change them.
Kind of an on-off situation. Either the sensor is working, or it isn't.

Chuck S

Got a spare $450 for new OEM sensors? Let us know what happens.

-- Chuck

windhund116

"I have an AP1 2002, spa yellow, and I do burn oil and my rear bumper is always covered in soot."

Changing O2 sensor will prolly not have any effect on oil consumption.

HarryD

That much I do know -- But I also know that a non-insignificant amount of the black stuff on my yellow bumper is a result of my oil burning issue -- I'm curious how the insides of my exhaust system (including the o2 sensors) look like after 15 years of burning oil and running super rich.

Re: $$450 in OEM sensors, per my research, they don't cost *that* much!

For AP1 2000-2003 the forums (and Denso's website) list these part numbers:
http://www.amazon.com/Denso-234-4124.../dp/B000IYA6W0 => DENSO 234-4124 => Upstream @ $92.74 on Feb '16
http://www.amazon.com/Denso-234-4601.../dp/B000C5WCPY => DENSO 234-4601 => Downstream @ $28.91 on Feb '16

Any other thoughts?

Slowcrash_101

O2 sensors should probably be changed around the 100k mile mark. You'll know if your O2 sensor is bad if you start getting fuel dilution in your oil, if you smell gasoline in your oil change it, don't wait for the code.

windhund116

Not sure why you'd smell excessive gas in oil, except if you were getting a lot of blow-by from the piston rings. How does putting a new O2 sensor help this issue? I think I'd let sleeping dogs lie, wrt O2 sensors and no associated CEL codes.

Thanks!

Billman250

My 03 has 140k on the original o2 sensors.

windhund116

How do the spark plugs look? If ok... I wouldn't worry about it.

Just my 2¢ worth.

zeroptzero

The downstream sensor won't affect air fuel ratios, just the primary. I would replace the primary sensor if I was getting high fuel dilution in the used oil sample. Do a used oil analysis and see how the results come back, they are pretty cheap to do.

But it stands to reason that the o2 sensors need to be changed at a certain mileage, what that mileage is can be anyone's guess.