P0420 code after Protect and Restore

[rvsarch]

All emission readiness tests have completed including catalytic converter, which cleared the permanent P0420 code. The pending and confirmed P0420 codes have not come back since they were erased. I'll probably use Cataclean again right before a planned trip to Maine. Since my wife drives so many short trips with the car, I'm going to use it once a week for a highway trip I normally make in my car, a 2007 Accord V-6 manual 6 speed coupe which consumes no oil. Going to try 5w30 Restore and Protect in the TSX to see if oil consumption decreases over the summer. VTEC actuator on the TSX can rattle on startup when the temps are in the low 20's, so I'll probably run 0w20 in the winter.

 

[himemsys]

I don't see how anything you pour into the gas tank can do anything for post exhaust manifold? Special fumes?

I'd guess weak O2 but you didn't show any voltage values. It's helpful to see the highs and lows values and the frequency in which they cycle. The post ac at one should normally not cycle much with constant throttle. Closed throttle it should drop out but bad cat and it will be eerily similar to the cycle of the primary O2 sensor.

Go to their website. They explain how it's supposed to work.
https://cataclean.com/how-it-works/

 

[John105]

This is a mysterious code and I always wondered how an ecu throws it. Is it cumulative, or instantaneous (the efficiency deficiency). The problem with this code is dealers tend to throw the baby out with the bath water and replace cats and 02 sensors which is expensive.

We have a GM where if codes are erased it can take 1,200+ miles for the evap to be ready. This code makes people want a new car

 

[Revving2Redline]

I received a notice from Acura soon after purchasing a 2011 Acura TSX Wagon, warning about oil consumption, extending the warranty and offering to replace the piston rings if oil consumption became excessive. They also suggested using only top tier gas and letting the car warm up before hard acceleration. Oil consumption has remained fairly constant at about 1 qt every 3k miles, so no warranty fix. I shortened OCI from the maintenance minder to 7,500 miles right away and then to 5,000. I did my last oil change using Valvoline 0w20 Protect and Restore for the first time and got a P0420 code for catalytic converter low system efficiency about a week later. I checked my oil and found that it had gone completely dark, so I drained it and put in 0w20 Kirkland. I suppose the “restore” part of the oil package loosened up a lot of carbon and I’m thinking it might have fouled the converter or sensors. I suppose the oil burning over 125,000 miles has not been good for them either. The car runs great and freeze frame at the time of the code shows a lambda of 1.009, short term fuel trim at 3.1%, and long term at -0.8 %.

I put in a bottle of Cataclean in a quarter tank of gas and drove 20 miles. Filled the tank and went on a trip of 100 miles at 70 to 80 mph, occasionally holding the transmission in 4th gear at about 3,600 rpm. No hesitation or drivability issues so converter is not clogged. Then I replaced upstream and downstream sensors with Denso, anticipating that I'd want new ones anyhow, in the event that I have to replace the catalytic converter. I cleaned the throttle plate and MAF sensor even though they looked pretty good. No evidence of exhaust or vacuum leaks and very smooth idle. I erased pending and confirmed codes, so CEL is off but permanent code is still there, because it's permanent. Fingers crossed.

View attachment 216208

replace cat and contact me for alternative to Honda expensive suggestions

 

[Revving2Redline]

It’s possible that your aft oxygen sensor is getting fouled by “THC” in the exhaust. Install a couple of these (Dorman 42009) on your aft oxygen sensor and your “Mary Jane” code could disappear.

View attachment 216484

a defouler might work

 

[wpod]

The 2.4 was the only engine choice for the wagon. A lot of opinions pro and con about using a thicker oil to combat consumption. I have also been reluctant to try an engine flush out of concern for the seals. I have zero leaks and colored concrete pavers where I park.

The thicker oil is some thing you need to try and if it works good and if it doesn't it is not any difference in the cost of the oil change

 

[rvsarch]

Just a follow-up: CEL / P0420 never returned. No pending codes. Readiness tests all report completed. Oil consumption has not changed, still about 1qt per 3,000 miles with Restore & Protect.

 

[John105]

Just a follow-up: CEL / P0420 never returned. No pending codes. Readiness tests all report completed. Oil consumption has not changed, still about 1qt per 3,000 miles with Restore & Protect.

The first time we got one, it was literally Christmas day 2022. The code didn't come back for another 10 months. Reset it, didn't come back for months again. As time went by, it began to come back more regularly. Also, no rhyme nor reason. Sometimes, 1,300 miles, sometimes, 80 miles. It's the 80 that's disconcerting.

I finally learned, and contrary to what we're taught. The internet is correct. In Calif, in PA, etc., one "CAN" pass emissions with 1 readiness, not ready. Face to face? Garages told me that's not true. My thinking was it doesn't matter what Drive Clean PA says, because the garage is the one that puts the sticker on the car. It took 2024 for it to finally click--the technician is making a decision on the safety inspection, he/she is not on the emissions. The car is plugged into their computer which is linked to the Commonwealth of PA. The system makes the decision. So whether or not the garage "feels" a car will or will not pass emissions if one I/M category is not ready, is irrelevant. It's not up to them.

So this year, I simply went in with 6/7 categories ready, EVAP not ready. PASS (again the problem is our GM takes 800-1300 miles for the EVAP to be ready and by then the P0420 is back--my other car, 70-80 miles. The third car I've never reset it in 17.5 years). Just my musings on this topic, can't wait to get a new car maybe 2026 or 2027. The more we drive what we have, the easier it is to plunk down the price of a new car these days (likely six figures). P.S. also didn't realize until this year, erasing the P0420 via the Autel, or disconnecting the battery, does not clear it out of pending. Only the car can do it. I knew newer cars were like this, but didn't know our 2011 was.