I replaced my son’s catalytic converter in the Kia Rio and replaced upstream and downstream with some Bosch O2 sensors. Works just fine. The old ones might have worked also, but I figured since I was doing the job, just replace them.
Replace O2 sensors with new catalytic converter?
- Thread starter NissanMaxima
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My first try to fixing of your issue, I would try would be run 1 tank of cat clean ( with a very heavy foot I might add, get that cat hot.) . Then change both upstream and downstream 02 sensors with Denso sensors from a known distributor. Then worry about the cat....IF needed. I highly doubt your cat needs replacing at 130K
Thanks all. I'm going to have the dealer run some diagnostics first and hopefully that will provide some guidance. As to the cat itself, I was going to order using their on-line system as it is already quite a bit below their parts counter price and then there is a 15% holiday sale through Monday. I'll ask them to save the old one and I see there are any number of on-line places that buy them. I appreciate the suggestions about Techron and Cataclean but it seems they are hit or miss. I'll have to digest a bit more.
Questions: If I proceed with the job and have them replace both sensors on the new bank 2 cat, what about the bank 1 sensors? I'm going to show my ignorance here, but will replacing two sensors on the new bank 2 cat and leaving the old bank 1 cat sensors cause any sort of imbalance in how the car runs? If I'm going to do this, I want to do it right. I don't want the new cat to fail because I didn't replace a sensor.
Finally, spark plugs are still original. It is on my list but the valve cover gaskets are leaking so this a major job I'm not looking forward to. Will worn spark plugs degrade a new cat?
PS car is a 2005 V6 highlander with the 3MZFE engine.
Questions: If I proceed with the job and have them replace both sensors on the new bank 2 cat, what about the bank 1 sensors? I'm going to show my ignorance here, but will replacing two sensors on the new bank 2 cat and leaving the old bank 1 cat sensors cause any sort of imbalance in how the car runs? If I'm going to do this, I want to do it right. I don't want the new cat to fail because I didn't replace a sensor.
Finally, spark plugs are still original. It is on my list but the valve cover gaskets are leaking so this a major job I'm not looking forward to. Will worn spark plugs degrade a new cat?
PS car is a 2005 V6 highlander with the 3MZFE engine.
end of the day you want the the CEL to go away and for it to run as good as reasonably possible right? Like most people there are financial constraints I assume?
- 100% #1: new OEM plugs (20 year, [?] mileage, and who knows how many hot/cold cycles. They are probably out of spec.)
- I would do the Cat clean and FI stuff first as to not chance fouling the new plugs
- Is this a coil on plug engine? Might need rebuild kits for them, but they are cheap
- Address the valve covers while you're in there. Oil is coming out? Something else like dirt/air can get in. Check/Clean PCV system also... First hand, I've seen two family vehicles, leaking/blown valve cover gaskets and their PCV systems were almost completely clogged full of gunk/oil/carbon.
- Sounds like you are using an independent shop? Make sure you get a discount for either the spark plug change or the valve cover gaskets... Both jobs, they are in the same "Neighborhood" At least half the work for one is already done doing the other. (I would be looking for the spark plug change as a no cost add on to the valve cover gasket, assuming you but the plugs thru them, that they are marking up at least 20%)
Yes, when I said hose them down, I meant the socket areas where the O2 sensors screw into the exhaust bits. Several days of spray + soak + drive could make a huge difference with the R&R.
Hammer drill for the converter and sparkplug non fouler for the rear 02.
Thanks. My plans were to use the dealer for the cat and sensor job, and tackle the spark plugs and gasket job. It just seems the cat would be miserable without a lift (even though I have jackstands). Plus I did want them to do the diagnostics.
If I want to go straight for cat replacement (pending diagnostics) rather than Cataclean or other cleaners, does it matter if those spark plugs get changed out first? Do worn spark plugs put undue exhaust load on a new cat?
And anyone have input on my question as to if I have them replace both sensors on the new bank 2 cat, if the ones on bank 1 should also be replaced to prevent any "imbalance" and provide optimum performance?
If I want to go straight for cat replacement (pending diagnostics) rather than Cataclean or other cleaners, does it matter if those spark plugs get changed out first? Do worn spark plugs put undue exhaust load on a new cat?
And anyone have input on my question as to if I have them replace both sensors on the new bank 2 cat, if the ones on bank 1 should also be replaced to prevent any "imbalance" and provide optimum performance?
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- Aug 3, 2024
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It can't help. Worn plugs can cause inefficient combustion resulting in excess unburned fuel, the cat's job is to reduce these unburned hydrocarbons. You can see how fresh spark plugs would ease the load a bit.
Like the dealer, I also reuse the sensors. Those sensors are not inexpensive and could have a lot of life remaining.
I would pay a shop for any exhaust work on an old car especially something like removing a cat. Money well spent IMO. Wouldn't be surprised if the studs on the manifold break.
That said, the dealer is going to charge a lot more than your local muffler shop would.
Leave bank 1 alone.
Thanks. I have watched tons of videos on replacing valve gaskets on the 3MZFE engine. It is not a trivial job due to what you have to do to access the rear 3 plugs, but one I'm contemplating doing myself. One fellow even went so far as to clean the carbon off the walls below the intake manifold after removing it. - but not sure if that is necessary or has any impact to car performance. When someone in the comments talked about just removing the lower gasket too to be able to throughly clean it combined with some bolts snapping, I about threw in the towel on attempting this job.
My inclination is to have the dealer proceed with the cat replacement and two new sensors so this CEL goes away, but now I don't know if I should delay having them do that until after I do this valve cover/spark plug job for fear replacing cat and sensors first and then running car with old spark plugs could cause accelerated degradation on the new cat. My gut feeling is that any accelerated impact would be marginal as when I've changed out spark plugs in the past in other cars they look decent with a gap almost spot on original value, but I'm no expert. The other thing on my side is the car doesn't see a ton of miles either.
you were saying earlier that the dealer had to perform diagnostics to confirm it was the catalytic. Did they do that already? I know you had a CEL code.
And yes replace the spark plugs before you get the new catalytic, if the plugs are old and misfire that can damage a catalytic. Also make sure you break in the catalytic properly, usually it takes idling the car until the radiator fan comes on, turn the car off, let it sit for a couple hours. I'm not sure how Toyota has their catalytics break in but that's how the no-name ones have it done.
The dealer is scheduled to do the diagnostics and then proceed with catalytic converter and sensor parts I'm going to have waiting for them in parts (I was going to purchase via Memorial Day on-line deals today). But if folks think those plugs should be replaced first, I may have to delay this job altogether and not order the parts today during the sale. I don't think I'm having any misfire - at least nothing I notice while driving and no codes with my Innova scanner. The only other code was a C1224 NE signal circuit the service advisor wasn't sure about. Withou any apparent plug-associated issues right now, are new plugs really necessary before proceeding with the cat?
Or, maybe this is an idea... On the 3MZFE engine, getting to those rear spark plugs is a real bear. From what I'm seeing on line, bank 2 is at the front of the engine. That is also where the front 3 spark plugs are located and super easy to change. So I'm assuming then those plugs are associated with bank 2 in the diagram linked? Maybe I could at least change out those 3 spark plugs that are presumably also associated with the bank 2 cat and I'd be good until I tackle the rear 3 plugs? See this link. Sorry, I can't seem to attach a pdf here. https://www.toyota-4runner.org/atta...ensor-bank-1-sensor-2-p0136-code-location-pdf
Or, maybe this is an idea... On the 3MZFE engine, getting to those rear spark plugs is a real bear. From what I'm seeing on line, bank 2 is at the front of the engine. That is also where the front 3 spark plugs are located and super easy to change. So I'm assuming then those plugs are associated with bank 2 in the diagram linked? Maybe I could at least change out those 3 spark plugs that are presumably also associated with the bank 2 cat and I'd be good until I tackle the rear 3 plugs? See this link. Sorry, I can't seem to attach a pdf here. https://www.toyota-4runner.org/atta...ensor-bank-1-sensor-2-p0136-code-location-pdf
I saw two yt tricks for removing O2 sensors.
Add a worm-gear hose clamp around the open gap of that special socket to help prevent it from spreading apart.
With a stone cold engine and exhaust, run it exactly one minute. The exhaust heats up more than the sensor, so the metal of the mount hole expands more than the sensor.
Add a worm-gear hose clamp around the open gap of that special socket to help prevent it from spreading apart.
With a stone cold engine and exhaust, run it exactly one minute. The exhaust heats up more than the sensor, so the metal of the mount hole expands more than the sensor.
