thegrouse

I was on a long road trip and I got this error code. I took it to a small town mechanic and he said it was the catalytic converter that was bad. He said they checked the sensors. He told me he could not be positive and recommended I take it to Lexus. I called my regular mechanic now that I have driven 2000 miles back home. He told me the same thing over the phone that it is more than likely the cat on bank 1. He told me it would be around 800 to do the job and it is 1.5 hours of labor. I am a pretty handy guy so I thought about tackling this myself. Has anyone done this? It looks like it is the back converter? I have located the OEM part for 375$ and I will need a few gaskets. If I do it I will post photos to advise any future folks on what not to do.

Bear1906

just curious, how many miles on your RX? I got same code on my 96 LS w/139K miles and getting similar story from mechanic.

thegrouse

I just rolled 98000 on the odometer

thegrouse

Well I just ordered the cat converter and both gaskets I will need. Has anyone changed the rear cat?

robbyk

Where did you order the cat from?

thegrouse

I bought a Toyota OEM off of Ebay. It was the best price

Grumpa72

I just got the P0420 Catalyst System Efficiency below threshold, bank 1 and the car has 110000. Have you done this yet and is your eBay part a real Toyota part? Advance Auto sells a generic, one-size-fits-none model for mid 100s but I am betting that there is a lot of fabricating to make it fit. Don't want to consider that.

What is the Toyota part number that you have for that?

Let us know how it goes and if you do it yourself.

Thanks,
grumpa72

thegrouse

The part I purchased was Toyota #2505120040. This is the rear converter. It should be here today and I may tackle it tonight. I have already removed the bottom skid plates to access the area. I have sprayed the exhaust flange and manifold bolts with PB Blaster to loosen them up. I am using the ramps to get under the vehicle. There is not a lot of room to take photos. I will post the results. If I can get some decent pictures I will take some.

Grumpa72

Well, I took the easy way out and had Lexus replace the Cat assembly. My bad back precludes some of the work I used to do and this was one I didn't need to. $830 out the door. I am happy with price.

thegrouse

Did it stop the problem? I am hoping it is just the cat.

Grumpa72

Stop the problem? Yes. I was going to get my car inspected and the OBD II threw this code. I checked everything, ran the car, deleted the code and it came back. I had the mechanic throw his more advanced machine on the car and three items came up as "not ready", Evap. control, Cat below operating efficiency and something else. Once I had the new cat installed and the codes erased, I went back to the mechanic and the car passed. The light has been off for two days now.

thegrouse

Well I tore into the project today. So far 2.5 hours and I have not got the old one out yet. A lot of cursing and one trip to the store for a 14mm deep socket and a u joint socket. I had one but I had to use two. The bolts on the manifold are very difficult to access. I had to tape the u joints to keep them from flexing. I had the RX up on ramps so I could work. I now need to go buy an external torx set to remove the studs from the exhaust flange into the cat. Ill update the thread as I progress.

thegrouse

I finished tonight. I think it took a total of 8 hours. I needed a deep well 14mm socket, 2 u joints, external torx socket and a bunch of extensions. Anyone know how long it will take for the check engine light to go off?

thegrouse

Well I took it out today and started and stopped a few times. The check engine light went out. I did not even drive 40 miles. Here is a quick overview in case anyone decides to change the Bank 1 Cat on the 2005 RX330 AWD. It took me about 8 hours total and I saved about 400$. I am going to scrap the old cat and I guess I will get about 20-40$ for that also. If I had to do it again I bet I could do it in 3 hours. I could not find any guide or instructions so I just had to learn as I went. This entire repair will be done from under the vehicle. I used ramps and jack stands for safety so I could get underneath. I highly recommend a set of gloves because it is very tight. I recommend a can of PB Blaster on the bolts before you begin. A good light is a must because the bolts are way up in there and tough to see.

The Bank 1 cat is the one between the firewall and the engine. There is an oxygen sensor on the top of this cat that will need to be unplugged once the cat is loose.

Step 1- Remove both of the plastic skid plates the cover the bottom of the engine.

Step 2- Remove the two bolts connecting the catalytic converter to the y pipe. These are 14mm deep sockets that thread onto studs. Once the 14mm bolts are removed use a external torx socket. I believe it was an E8 to remove the studs holding the flange to the cat. Set these bolts and studs aside. Now the cat is loose from the y pipe.

Step 3- Remove heat shield. There is a metal heat shield that covers the manifold bolts. This is held on by 3 10mm bolts. Remove the heat shield and set aside with the 3 bolts.

Step 4- Remove all 6 of the bolts holding the manifold onto the engine. This is where it gets tricky. The top bolts are fairly easy to access but the bottom ones are pretty tough. These are all 14mm bolts and they need a deep socket on them. You will need around 18" of extension and either a wobble extension or a U joint or both. I had to use a combination of the wobbler and the U joint to get square on the bolts.

Step 5- Remove support brace from CAT. There is a tube like support bracket that attaches the CAT to the engine. This is removed with 2- 14mm bolts. Remove and set aside.

Step 6- The CAT is now free. I was able to move it a little bit so I could access the oxygen sensor plug. You will see the sensor plugged into the top of the CAT and you will need to follow the wire up into the plug that is above the CAT. This is accessed by reaching up way up in the and disconnecting the plug. Now that the plug is disconnected the CAT is free. I was not able to remove the CAT at this point. There was not enough room for the CAT to clear the studs. I had to remove 2 studs going into the motor using the E8 Torx socket as used earlier. I also had to use the wobble/u joints to access the studs.

Step 7- Remove the catalytic converter and set aside.

Step 8- Remove old gasket that goes in between the block and the CAT.

Step 9- Remove donut gasket the goes in between the CAT and Y Exhaust Pipe

Step 10- Remove the Oxygen sensor from the CAT. Remove the heat shield using a 10mm socket. Install the shield and sensor onto the new CAT. The new Bank 1 CAT is Toyota part 2505120040

Step 11- Install new gasket onto the engine studs. Toyota Part 1717320030. It should stay in place with a little coaxing. The gasket can only go on one way.

Step 12- Install new gasket onto the exhaust flange. Toyota part 9008043036

Step 13- Lift the CAT up into place. This requires a little patience. The CAT will need to be
squeezed into position just right. Before you try to put the CAT on the studs attach the Oxygen sensor back into the plug. Once you are close to putting it on the studs make sure the engine gasket has not fallen off. Gently put the CAT onto the studs and put the other end on the exhaust flange.

Step 14- Reinstall the 6 bolts and studs into the engine block. Once they are all started tighten them up a little. Since they are on the exhaust I didn't want to make them too tight. I did not use a torque wrench.

Step 15- Reinstall the studs into the CAT through the exhaust flange. Once the studs are in place install the 14mm bolts. Tighten down not too tight. Sorry I don't have any torque specs.

Step 16- Install support bracket using the two 14mm bolts. Install heat shield with 3 10mm bolts

Step 17- Reinstall all skid plates

Step 18- Start engine and watch for smoke. The new converter will smoke as it burns all the packing grease/oil that is on it. I took mine out for a 10 mile drive and checked it once I was done. The smoke should stop. You will see the smoke coming from in between the engine and the firewall.

You are now done. If your vehicle had the P0420 code it should go away with a few driving cycles. I hope this helps someone in the future if they decide to tackle the job themselves. I will update if I have any additional P0420 issues.

thegrouse

I took the old CAT to a scrap yard and they gave me 65$. Be sure not to overlook this.