I bought Prius 2007 168k mileage in 2021, now 174k. After few month, my cat converter was stolen. Then, I installed an after market cat converter and gave me P0420 code pain for 2 years. in 2023, I bought another after market cat from ebay that guranteed P0420 issue will be solved and it did. Since last week, my car is showing CEL and found out it's P0420. last 2 days, I have been running car, recording and clearing Freeze frame DTC and on-board monitoring. Though both time on-board monitoring showed Catalyst Monitor Bank 1 failed but the VALUE is different. So my questions are: 1. What are the causes of showing P0420 code other than Aftermarket Cat? 2. If Cat is the problem, then why On-BoardMonitoring-Day-2 (latest) is showing better values than On-BoardMonitoring-Day-1? 3. Why is my oxygen sensor always show "Incomplete"? How do I make that complete? FYI, I live in New York that implemented CARB law with CA and other 9 states.
the problem is you're buying the cats from eBay. Why just buy the cats offered from a muffler shop, you can be sure that it will last.
They don't last. Had an aftermarket one for about 2 years before p0420 and now got another so it's ok again. As in so many areas of life: 'You get what you pay for.'
Unfortunately I did not know anything about the catalytic converter, its purpose and usage. I have learned so much from this forum reading tens of posts for several days. However, I have found Magnaflow selling CARB compliant converter. I have read somewhere that Prius has 2 cat converter: front and back. So which one I need? Or I need both?
The cat monitor test is like someone with a stopwatch having you run a 1 mile. There are lots of reasons why you won't run the exact same time from one day to the next. One day might be a little faster or slower than the last. Overall, if you're a track star you'll have consistently "great" numbers, but if you're a couch potato, the numbers will be "bad". Many aftermarket cats are couch potatoes- maybe it can "sprint" for a short time but doesn't have the stamina to keep working year after year. This assumes that: There are NO exhaust leaks near or upstream of the A/F or O2 sensors. The A/F and O2 sensors can properly report full rich and lean conditions. The engine runs properly (no misfires, fuel trims 0 +/- 10%, and "no" excessive oil consumption). To complete the O2 sensor monitor, drive the car. Can take a few days of mixed steady cruise highway and local speeds. If you want, google "generic obd drive cycle" for a general guide line. There's probably specific driving instructions for that specific monitor, but I have never needed them. Posted via the PriusChat mobile app.
the prius has 2 cats, primary and secondary. The primary is being monitored and that's the one causing the p0420 code and that's the front cat. The secondary oxygen sensor that checks your primary cat is between them. In non-CARB states this can be fixed by a spacer and the secondary cat can be replaced with a straight pipe or gutted.
'Fixed' in this case meaning the car prevented from noticing that the cat doesn't work, if the 'fix' succeeds.
So, I need front catalytic converter only, right? I don’t want to use spacer. It won’t help me to pass inspection in NY.
"doesn't work" and "not efficient" are 2 different things. A non-working cat basically melted or broken into pieces that it clogged the exhaust and will not let the engine run, a P0420 however refers to the efficiency not being meet, cat is still operational, engine runs and no drivability concern.. you're just polluting NY... non-carb states don't mind the pollution. So tricking the computer to lower the bar is acceptable if the cat is still in one piece (or you could put a black tape on check engine light and have a good night sleep ) yes, I do understand the pain living in CARB states..but we love you for loving earth..
I have seen the Walker 16337 work in gen2s. It has both cats for $300. Others also agree. Most likely the Walker 16337 will not last 25% as long as oem. Especially if your car is burning oil. However you live in NY and they require oem catalytic converters, not just no codes. Unless you know a guy.
A cat that won't let the engine run would certainly be a problem. All the same, a cat that doesn't do what a cat is for could fairly be said not to work.
