2005 CATALYTIC CONVERTER 250k Miles- Rid Codes P0420 catalytic converter & rear O2 sensor

I just replaced the catalytic converter to my 2005 Prius. My Techstream noted 2 codes active on my dash since I bought the used car APR17: P0420 - or Catalyst System Efficiency Below Threshold (Bank 1); specifically, catalytic converter and rear O2 sensor. Since my car is at 249k miles, I figure I do the “big ticket item” first, rather the cheaper rear O2 sensor. My girlfriend talked me into it as she explained the coded-faulty rear O2 sensor could be in great shape but affected by a likely faulty catalytic converter that feeds it. I mail ordered for a $150 part and went at it.

1. JACKED UP CAR & JACKS. I left the jack under the car, as a back up just in case either jack stand gives out.

2. CUT PIPE. I picked up a loaner tool set that both cuts & expands pipes. I cut the pipe at the flat section after the second bulb, giving me more room to work with, should I need to cut more. I believe the pipe was a 1 7/8” width.

3. REMOVE REAR O2 SENSOR. Used a 20m socket to remove the rear O2 sensor.

4. REMOVE FRONT FLANGE BOLTS. This was a challenge as both bolts were inset deep and also rusted and spring-pressured in tight. WD-40 helped but I had to incorporate a cheater pipe, as it was tight conditions under the car and jack stand vice car lift.

5. REMOVE CATALYTIC CONVERTER. Interesting seeing the catalytic converter removed. Pretty straight forward. A good amount of white speckled granules fell when I inverted and tapped at it.

6. CUT & FLARE NEW CATALYTIC CONVERTER PIPE. With the pipe expander tool, I flared the pipe. Not having a vice forced me to improvise and place a few 1.5cm notches on top for expansion.

7. REPLACE NEW CATALYTIC CONVERTER. First I sprayed down the exhaust manifold interior with carburetor cleaner. With 2 bolts, I now I bolted down the front of catalytic converter.

8. MERGE PIPES. With the front anchored nice, I merged both rear and front pipes: male-female connection with a tightened U-bolt.

9. CLEAR CODES, TECHSTREAM. No more P0420 dash lights.

10. ROAD TEST. The road test was for 2 miles and i took the car up to 60mph. It didn’t trigger any return codes, but was loud at where I merged the pipes. I redid the merge by applying 3layers of heat tape, then reapplied the U-bolt. So far so good. I will later report if I have any leakage/regression.

 

TMR-JWAP,
Thanks for the feedback. You are correct, those U-bolt ends are dangling a bit low.
Yeah, my girlfriend took a look at my pics and had similar comments about my mods. She offered up her welding torch next week when i get into her town. Im still renting, and not totally ready to commit to a mig welder, yet. I'm still feeling queezy over a hefty floor jack that i purchased last weekend; she's still queezy over my inability to commit. ; )

Cheers.

 

Exstudent,
Thanks for the insights.
I can definitely see how the heat tape will be a temp-fix for +3months. First time doing this procedure, so I am definitely seeing the whole process. It was good to see how it "could" be done without welding. A ref vid to show pipe tapering; this would've produced a tighter male-female pipe-fit and reduce the need for adhoc pipe notches and heat tape...

.... even though i ultimately will be resorting to a permanent fix-weld.

I will be getting my aftermarket cat welded this weekend at my gf's house; she's got welding tools. Been on the road now for >50miles without relapse of dashboard maintenance lights. I will keep you all posted on any updates to cat's durability; hope it goes longer than 1year. ; )

Yeah, i guess the word "big ticket item" is definitely subjective. However, I got the car for just $1300. I will have a lot to ponder, if i encounter car fixes of your magnitude. Count me lucky--- for sure.