When to replace O2 sensors??

**StuntmanMike** · 08-20-2010, 02:35 PM

Is there a certain age or mileage when the O2's should be replaced?

My car seems to run great, although a bit rough at idle (and has done so since I got it at 65k 3 years ago), and I don't have any SES light.

I DID get a SES light 2 years ago, it was the cat code, and I got them replaced at a dealer under warranty. No lights or problems since then.

But I'm creeping up on 100k, and I was wondering if I should think about replacing them. My mileage isn't quite what I think it should be (averaging around 22 so far this summer), and I wonder if myabe degraded 02 performance is the cause.

Should I think about changing them, or is it a "if it ain't broke, don't fix it" part.

BTW I just hit 150k on my '97 Jeep, I've had it since 40k, and I'm still running original O2's on that too. Runs great.

**pajeff02** · 08-20-2010, 02:41 PM

Anything over 80,000 miles is the general replacement window. Their performance degrades over time.

**dav-02ws6-m6** · 08-20-2010, 06:01 PM

Originally Posted by pajeff02

Anything over 80,000 miles is the general replacement window. Their performance degrades over time.

agree my car only had 72000 miles when one of them went out.

**cammed goat** · 08-20-2010, 06:03 PM

This is good to know as I am just hit 80k this week.

**StuntmanMike** · 08-20-2010, 08:19 PM

Cool, thanks for the info.

So should I be looking at Bosch or Denso?

**pajeff02** · 08-21-2010, 06:04 AM

The Bosch 13111's work nice. But, if you do not have LT's, plan on using zip ties to secure the extra harness length.

**StuntmanMike** · 08-21-2010, 01:24 PM

Our cars have four, correct? Before cat and after cat?

Are the 13111's before cat?

Thanks.

**qwk93ta** · 08-21-2010, 02:12 PM

I had Bosch on my 93 T/A and they worked like crap, replaced them with AC Delco no more problems. I just changed mine on my 00 WS6 with 57k miles.

**StuntmanMike** · 08-21-2010, 02:36 PM

Originally Posted by qwk93ta

I had Bosch on my 93 T/A and they worked like crap, replaced them with AC Delco no more problems. I just changed mine on my 00 WS6 with 57k miles.

Notice any difference in the way that it ran after you replaced them? And did you replace all 4, or just 2?

**Firebirdjones** · 08-21-2010, 03:09 PM

Most tuners will tell you to replace them every 40-50,000 miles. Over time they do tend to get lazy at trimming fuel. Sometimes not enough to set a slow switching code.
They are wear items just like sparkplugs.

**pajeff02** · 08-21-2010, 04:44 PM

Originally Posted by StuntmanMike

Our cars have four, correct? Before cat and after cat?

Are the 13111's before cat?

Thanks.

The front sensors are what control fueling. The rear units simply tell the PCM if the catalytic converters are working properly. Personally, I would only replace the front ones. The rears I would run until they trigger a fault code and set the SES light.

**StuntmanMike** · 08-21-2010, 04:47 PM

Originally Posted by pajeff02

The front sensors are what control fueling. The rear units simply tell the PCM if the catalytic converters are working properly. Personally, I would only replace the front ones. The rears I would run until they trigger a fault code and set the SES light.

Ok, that sounds good. I was hoping to onlyhave to do one pair, and I was thinking the front ones.

I found the 1311's on Ebay for $46...seems like a good price, I'll have to order them.

Thanks for your help!

**pajeff02** · 08-21-2010, 04:48 PM

Originally Posted by StuntmanMike

Ok, that sounds good. I was hoping to onlyhave to do one pair, and I was thinking the front ones.

I found the 1311's on Ebay for $46...seems like a good price, I'll have to order them.

Thanks for your help!

I paid $73 each for them at Autozone. That is a good price you found.

**StuntmanMike** · 08-22-2010, 05:42 PM

I went to Autozone today to find out just how long the 13111's were - WOW! 50" !!

The 13444's (stock part number) are only 16" long.

So what do I do with the extra 3 feet? Coil it up and hang it out of the way? I haven't had a chance to look under the car, but is that possible to do while keeping it safely away from the exhaust?

**35th-ANV-SS** · 08-22-2010, 07:04 PM

Yes, like Jeff stated, you just have to tuck it up and use something like zip ties to keep the access secure and out of the way of anything hot that could melt the wiring. And just so you know, the rear O2 sensors are interchangeable with the front two even though they monitor different things

**Firebirdjones** · 08-23-2010, 10:48 AM

Originally Posted by StuntmanMike

I went to Autozone today to find out just how long the 13111's were - WOW! 50" !!

The 13444's (stock part number) are only 16" long.

So what do I do with the extra 3 feet? Coil it up and hang it out of the way? I haven't had a chance to look under the car, but is that possible to do while keeping it safely away from the exhaust?

The 13111's are generally used for long tube headers so an extension harness isn't needed.
If you are still running stock manifolds then the 13444's are what you want. No need for the 13111's unless you are switching to long tube headers.

**bobbyd** · 08-23-2010, 01:58 PM

if you can try to go with Denso's. i have read so many hit and miss with the bosch sensors.
i myself replace miine with one of each and im going to be replacing the bosch with a denso. i think the bosch is a little slow at times.

**StuntmanMike** · 08-23-2010, 02:52 PM

I ended up going with the stock length Denso's. I found them at Rock Auto for 38 bucks each, then I found a 5% off coupon code online. Total with 3 day shipping was 80 bucks and change.

I see the value of the 13111's in not having to run extensions, but I have no plans at this time to run long tubes. Maybe in the future, but before that I want to do a new converter, so headers are a few years out at the minimun. I just don't want to deal with all that extra harness length right now.

**bobbyd** · 08-23-2010, 07:59 PM

Originally Posted by StuntmanMike

I ended up going with the stock length Denso's. I found them at Rock Auto for 38 bucks each, then I found a 5% off coupon code online. Total with 3 day shipping was 80 bucks and change.

I see the value of the 13111's in not having to run extensions, but I have no plans at this time to run long tubes. Maybe in the future, but before that I want to do a new converter, so headers are a few years out at the minimun. I just don't want to deal with all that extra harness length right now.

good choice man. if you do end up going with LT's in the future just get some o2 extensions. pacesetter makes some.