P0420 - Diagnosing O2 Voltages and Cat Temperature

Upstream is higher than the conventional #, but I don't know if a Primus adheres to the common convention.

A fluctuating downstream is indicative of poor cat performance. Since they tend to be inexpensive, I recommend you replace the downstream with a bosch or denso OE style sensor. If that doesn't change things, almost certainly the cat.

 

Not familiar with that test method.

Oil burning is a major contributor to cat failure.

 

You should reset your battery or erase all the codes after the cleaning of the cat.

What amount of the acids did you use and how much water did you mix it with? How did you keep the water that temperature for 12 hours?

 

You would disconnect the 12v battery to reset the lights. Disconnecting the hybrid battery momentarily never does anything to the car.

How many gallons did you end up making?

 

The last person that did this mixture and posted made around 6 gallons of this stuff and soaked it for 6 hours. I'm not sure how you were able to get away with making only 1 gallon and soaked the entire cat.

Maybe you have to make more solution and let it actually rinse out the contaminants.

His was only successful for about 3000 miles before the light came back on. But he didn't have the right temperature water for the 6 hours.

 

he soaked the cat in the solution. He did not pour the solution into the cat

I think it's important to have enough solution to dilute and rinse out the contaminants in the cat while you agitate it.

 

Can you say more about what kind of gauge you used for this, and how you used it?

I ask because I once saw a youtube vid where somebody showed using an IR temp gun with a laser guide spot, and was clearly just putting the laser spot down through a narrow gap between heat shields and thought he was measuring cat temperature that way.

The only thing that video was showing was that somebody had apparently never opened the manual for his IR temp gun, or wondered what the distance:spotsize chart on the side of his gun was for. Spoiler: you can't do it that way.

-Chap

 

You might have to repeat the process.....with more fluid. The way you did it, all the contaminants that was removed had no place to go. Also all the contaminants mixed with your acid bath probably changed the formula significantly because you had so little fluid to work with.

 

create a new thread with those codes, you'll get better response on them that way.

 

Upstream voltage is "high" because it is a "Wide Band" 02 sensor, the set voltage differ greatly from one OEM to another and in some cases even from one sensor brand to another; but normal is ~2.5V (2.0v - 3.0v) and varies during operation slightly.

Modern ECU's use the "wide band" Heated Exhaust Gas Oxygen (HEGO) sensor types to more accurately monitor and therefore control Air-Fuel Ratio (AFR), providing better engine life, economy and performance.

The second O2 sensor is a run-of-the-mill "Narrow Band" sensor and it's just there for emissions verification as you discovered with your "Catalyst Efficiency" DTC.

Subaru, Honda and from what I am learning Toyota have VERY tight limits on Catalytic Converter performance and will set a DTC even when the system is controlling emissions to WELL within mandated limits. Unfortunately, I am not familiar enough with these issues on a Prius to provide any solutions, except that an exhaust leak upstream of the catalytic converter can cause the DTC you have, as well as a worn oxygen sensor or cat converter.