O2 Sensor - Code P0135 - Replace all? (1 Viewer)

[lhommec13]

Got a CEL that I had my mechanic scan recently. I forgot the exact code number, but remember him telling me I need to replace both rear (post-cat) oxygen sensors. Sounds simple enough, but here's the backstory.

I've been in the habit of calculating MPG after each fill-up since getting the truck in 2009 and average around 12MPG based on roughly 60% city, 40% highway. The kicker is that I'm still getting 12MPG even two months after the CEL came on.

What I wonder is this: Will changing the o2 sensors actually improve my MPG? Sure I expect it to clear the CEL, but what can I expect as far as MPG are concerned? For full disclosure, I had DT headers installed roughly around the same time the CEL came on. Most likely related?

 

[chrisratz]

Based on my readings in this and other threads, I don't know how the rear sensors would affect your fuel economy. My knowledge on the subject is pretty weak but its my understanding the rear sensors just throw a code when they detect emissions that are not within an acceptable range. Only info received from the front sensors is used to tweak the air/fuel mix.

Got a CEL that I had my mechanic scan recently. I forgot the exact code number, but remember him telling me I need to replace both rear (post-cat) oxygen sensors. Sounds simple enough, but here's the backstory.

I've been in the habit of calculating MPG after each fill-up since getting the truck in 2009 and average around 12MPG based on roughly 60% city, 40% highway. The kicker is that I'm still getting 12MPG even two months after the CEL came on.

What I wonder is this: Will changing the o2 sensors actually improve my MPG? Sure I expect it to clear the CEL, but what can I expect as far as MPG are concerned? For full disclosure, I had DT headers installed roughly around the same time the CEL came on. Most likely related?

 

[lhommec13]

Based on my readings in this and other threads, I don't know how the rear sensors would affect your fuel economy. My knowledge on the subject is pretty weak but its my understanding the rear sensors just throw a code when they detect emissions that are not within an acceptable range. Only info received from the front sensors is used to tweak the air/fuel mix.

That actually makes perfect sense. Had I taken a moment to think more about it, I probably would have come to the same conclusion. I guess I should just replace the rear sensors and clear the CEL.

With that said, who has experience with changing out the rears? How many 's? Thanks in advance!

 

[2000UZJ]

Just got a P0135 today. It's my 2 year old $40 Bosch O2 sensor. Looks like I'm going to throw another one in there and go for another 2 years.

 

[super90]

Just got a P0135 today. It's my 2 year old $40 Bosch O2 sensor. Looks like I'm going to throw another one in there and go for another 2 years.

So why not just get at OEM one for $100 that lasts 10 years? Seems you would be ahead of the game.......

 

[2000UZJ]

So why not just get at OEM one for $100 that lasts 10 years? Seems you would be ahead of the game.......

I'm going OEM now. I thought about it after I posted.

 

[phsycle]

They're more like $57/each on Amazon. (Denso part number 234-4169) Courtesy of this thread: https://forum.ih8mud.com/100-series-cruisers/460524-denso-o2-sensor-part-numbers.html

 

[calskibum]

CEL and P0135 on 99 LC

Resurrecting an old thread. I got a CEL and P0135 today. After clearing the CEL, it came back again so it look like my O2 sensor is needing replacement. Here are a couple of question hoping for some input:

1) Does continue to drive the LC with the CEL on and P0135 for a bad O2 sensor damage anything? I won't be able to get the parts and replace the sensor for a week or two, so I'm wondering if the LC can still be driven in the meantime without negative effects.

2) Some posters in the thread had mentioned getting lowered mpg after replacing with the Denso sensors. Have these posters regained their mpg back?

3) For those using Denso O2 sensors, how's their longevity?

 

[TXLX100]

Is there a consensus about whether replacing O2 sensors before they fail increases MPG? It seems to work for some and not for others.

Has any thought been given to the different fuel blends around the country? Years ago, when ethanol in the fuel became more prevalent, I noticed a significant decrease in MPG (at least 10%). I'm curious if there is more or less ethanol (or other stuff) in the different fuel blends across the country that could cause a significant difference. I don't really have a good fix on the MPG of our LX because my lead foot wife drives it most of the time. I think it averages 11/12 in the city and probably 15 on the highway, in Texas.

 

[divejoe]

So four Denso sensors? Anybody has the diagram with the locations? Thanks!

 

[Gnarwgn]

So four Denso sensors? Anybody has the diagram with the locations? Thanks!

yes - ordered off Amazon from Denso (seller).

Look at Amayama parts diagram, or others. They are pretty easy to find. If you know what to look for you can see the front 2 through the wheel wells. Take off the shields and crawl under, the rear 2 are near the cat shields. Not hard to find.

 

[divejoe]

yes - ordered off Amazon from Denso (seller).

Look at Amayama parts diagram, or others. They are pretty easy to find. If you know what to look for you can see the front 2 through the wheel wells. Take off the shields and crawl under, the rear 2 are near the cat shields. Not hard to find.

Thank you so much!! Was able to replace the circuit bank 2 sensor 1 (passenger side before cat). Used a bosh sensor instead of Denso. Still had the error code after replacing it so not sure what the problem is. Probably will try to install the Denso and see if it goes away.

 

[77mustard40]

I cleared my code with my code reader then disconnected the battery while replacing the O2 sensors (I only replaced the upstream sensors on each side) then reconnected the battery and let the truck idle for 15 minutes before driving it. Noticeable improvement in performance and fuel economy.

 

[TheLCProject]

Thank you so much!! Was able to replace the circuit bank 2 sensor 1 (passenger side before cat). Used a bosh sensor instead of Denso. Still had the error code after replacing it so not sure what the problem is. Probably will try to install the Denso and see if it goes away.

It took my truck about 20 miles of driving to clear the code on its own after replacing the sensor. I used a Toyota part and not Bosch or Denso.

 

[wsudu]

Thank you so much!! Was able to replace the circuit bank 2 sensor 1 (passenger side before cat). Used a bosh sensor instead of Denso. Still had the error code after replacing it so not sure what the problem is. Probably will try to install the Denso and see if it goes away.

This is what I did, I either ordered from Amazon or advance auto. The Densos were fine. I was getting a code that was indicating the O2 sensor but once I replaced it, I still kept getting the same code and after digging, found it was actually the sensor above it which was the air fuel ratio sensor actually throwing off the O2 sensor. I just replaced them all. It's been 2 1/2 years no problems.

 

[divejoe]

This is what I did, I either ordered from Amazon or advance auto. The Densos were fine. I was getting a code that was indicating the O2 sensor but once I replaced it, I still kept getting the same code and after digging, found it was actually the sensor above it which was the air fuel ratio sensor actually throwing off the O2 sensor. I just replaced them all. It's been 2 1/2 years no problems.

Do you have the part number? Is it just one of those? Thank you!!!

 

[wsudu]

Do you have the part number? Is it just one of those? Thank you!!

The air fuel ratio sensor is 234–9051 and the oxygen sensor is 234–4260. 2 of each. That was for 2006 LX 470, not sure if yours would be different.

 

[divejoe]

You were right 2006 is different than 2001. All of them are referred to as O2 sensors in mine. Really appreciate your help!

The air fuel ratio sensor is 234–9051 and the oxygen sensor is 234–4260. 2 of each. That was for 2006 LX 470, not sure if yours would be different.