2005 Honda Pilot
Our daily beater car that has been with us for 17 years now has an engine code showing:
P0420 (1/1) Catalyst System Efficiency Below Threshold (Bank 1) DTC Severity 2 of 3 fault.
The auto parts store guy who used the scan tool said it was the 'bank 1 O2 sensor fault'. Looking it up on-line it looks like a catalytic converter fault. Videos show it can be related to other things and replacing the cat might not be the proper course of action.
Can the team here advise on next steps?
Y-pipe replaced and saw question on recent video!! Thanks Scotty!!
Code has not come back, car is quieter, and it does not smell like exhaust while driving!
Job was not that bad but man-oh-man were the bolts rusty.
Exhaust: Has leak and is noisy due to Y-pipe rust
If you looked up the code you should have found that exhaust leaks are a common cause for P0420. Fix that first.
https://www.obd-codes.com/p0420
https://practicalmechanic.com/2020/03/14/how-to-fix-a-p0420-error-code-on-a-toyota-corolla/
Step 2 if the exhaust leak doesn't fix it would be replace that 02 sensor. But an exhaust leak could be throwing that sensor off in the first place.
Some additional information on the car and summary of issues:
Car: 2005 Honda Pilot
Engine: 3.5L V6
Miles: 233,000 miles
Owner: We have owned since 22,000 miles
Owned since: 2006
Fault code: P0420 (1/1) Catalyst System Efficiency Below Threshold (Bank 1) DTC Severity 2 of 3 fault.
Drivability: not issues prior-to or after fault code appeared
Exhaust: Has leak and is noisy due to Y-pipe rust
Thanks Chuck!
I was curious on feedback here prior to opening up the parts cannon, trusting the guidance here first.
That may or may not be the problem, but leaky exhaust needs to be fixed anyway.
I ordered exhaust parts to replace the Y-pipe. Looking at the fault kit, there are 3 cats on the car and bank 1 and 2 are ahead of the Y-pipe. We'll see what happens and I will report back in a couple weeks after they arrive and are installed!
Replacing y-pipe now. Amazed at how rusted the nuts on manifolds were yet came off with heat. They didn't even look like nuts, just blobs of rust! The studs looked like they were 1 year old and appear to be OK for the new pipe and nuts. The catalylitic fasteners were another chore but they are ground off and punched out.
Meanwhile, the engine code disappeared a week or so ago. LOL!