What’s Wrong with Non-OEM CATs?

August 8, 2019


What’s Wrong with Non-OEM CATs?

The Stoichiometric graph lists the poisonous gases in details. In this case, why did they come up with 14.71 air-fuel ratios as the store geometric level? This is due to a happy medium between HC (Hydrocarbon), CO (Carbon monoxide), and NOx (Nitrogen oxides).  When talking about the catalytic converter, we know that we have three precious metals inside. There is Platinum, Palladium, and Rhodium. Obviously, Platinum and Palladium are used to clean up the HC & CO. Radium is actually used to clean up the NOx levels on a vehicle. So a lot of times techs ask how do you put on these Aftermarket Converters on, the P0420 code keeps coming back, or how to diagnose a P0420 code easily?

Now there could be a number of issues like it could be an exhaust leak or the CAT Sensor (in rare cases). Most of the time, it turns out to be the Catalytic Converter. A lot of times our scan tools on the market that shows the Pre/Post CAT O2 Sensors for Bank 1 and Bank 2. They’re pretty much mirroring one another and it’s telling you over all the Catalyst Efficiency on Bank 1 are only 8% while Bank 2 with only 11% range. Now seeing there is a severe problem with the catalytic converter needs to be replaced. Keep in mind, states like NY and CA need catalytic converters that are C.A.R.B certified to meet emission regulations.

Remember there are drivability emissions calculators that can be found online.

(i.e the Drivability Guys)

  Remember how does a computer know if the catalytic converter is out to lunch or not. The PRE CAT 02 Sensor should be switching Rich to Lean so it should cross that 500 thresholds in a hundred milliseconds or less. That’s an OBD2 term, so anything ‘96 and newer that’s what you’d expect to see.  I’m using lab scope to see that thing toggle Rich to lean in a hundred milliseconds or less. It then we’ll compare the PRE CAT O2 Sensor to the Post CAT O2 sensor and what it’s basically looking for is the Post Cat O2 sensor is 30% or less in the amplitude of that of the PRE CAT O2 Sensor. One last thing, if you don’t happen to have a scan tool that has the fancy test this is one of those drivability calculators that I referred to a couple of times here.

Three Precious Metals

In conclusion, Aftermarket Converters currently lack Platinum, Palladium, and Rhodium, which is why the price tag is so much cheaper. The next time you’re thinking about putting an Aftermarket Converter in a car just go ahead and plug it into the Catalyst Efficiency Calculator or Scan Tool. Any Technician can kind of get a good idea just exactly why that aftermarket converter is so much cheaper than a factory converter. You’ll see how close the NOx, HC, and CO are with overall percentages as well as how close they are to fail. They’re going to turn the light off for you, but how long is always the question.

Special Thanks to Ozzstar.

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