6 ms·

unless the cost to extract the metals from a catalytic converter is > $95, and the replacement is a spare catalytic converter (from a junkyard say)

sokoloff 5y ago
Used converters are not legal for sale for installation unless they’ve been individually tested for function. There are numerous catalytic converters for sale on Amazon around the $100 price point. If there’s $500 of rare metals inside, I think I’ll supplement my tech job and do a bunch of drop shipping from Amazon to a scrap metal place someplace.
- mindslight 5y ago
  I've heard from a mechanic that the aftermarket cats don't work particularly well, and they're basically just for fulfilling the legal requirement to repair an emissions system as designed. Presumably they skimp on the expensive catalyst. Does the CA smog test for newer cars still include an actual sensor stuck into your tailpipe, or is it all ODB2? And does the typical emissions system have any sensors past the catalytic converter?
  - brianwawok 5y ago
    Many (most) states never actually hook cars up to sensors. So for most of the country, a half working converter looks right, at the cost of our air quality….
    - oasisbob 5y ago
      And, some states which used to have emission tests like Washington have discontinued them entirely, via OBD or sniffing. Justification was diminishing returns as the distribution of cars on the road has naturally changed and eliminated many problems.
      - lotsofpulp 5y ago
        Yes, people in the states without testing can just straight pipe it for $10 and half an hour of labor rather than shell out thousands to get a new cat installed. Save money and future proof yourself from further thefts.
      - Scoundreller 5y ago
        The mass testing model was always dumb because the state/emission testing vendors have test results for every car and should be able to predict which model/years need testing and which don't. Instead out of "fairness" or greed, they'd require everyone to get every car tested every X years after Y years of age when sampling would make a lot more sense.
        mindslight 5y ago
        Erm what? The emissions and safety properties for every vehicle model are regulated at design time (in anticipation of sale). The point of periodic testing is to make sure that every instance of a design remains as-designed, and has not failed through damage, insufficient repair, or deliberately. How else would this be discovered?
  - slobiwan 5y ago
    The last time I took my car in for a (California) smog check, they definitely stuck a sensor up the tailpipe. Also run the engine for fixed duration at several set speeds to get a variety of readings, on a dynomometer (a treadmill, basically) to simulate actual driving speeds.
    - kube-system 5y ago
      I think California is the only state that does this. Most other states do visual inspections or OBD-II tests.
    - dmckeon 5y ago
      Apparently Californians get a double whammy on cat thefts - a generic replacement cat converter for most states costs about $500, but the exact same replacement cat that is certified by CARB (California Air Resources Board) runs about $2k. This explains why older CA cars are more likely to be totaled out by a cat theft.
  - mgarfias 5y ago
    Anything made after ‘96 has an o2 sensor downstream of the cat to verify the cat is working. If it stops working the ecu will toss a p0420 code and turn on the check engine light.
    - mindslight 5y ago
      Is it physically downstream on another part though? It's been a while since I've been under a car but I remember seeing what I thought was the O2 sensor, and it was part of the whole catalytic converter assembly. If it comes as part of the same assembly, it would be easy enough for new ones to include a fake O2 sensor.
      - mgarfias 5y ago
        It screws into either the cat, or the pipe right behind it. But it’s a separate part.
    - sokoloff 5y ago
      Those downstream checks are easily defeated in most cars. They work fine as a signal that the converter isn’t working iff you’re like most people and not trying to defeat them. If you’re trying to defeat them, a simple RC or other timer circuit on the signal pins and enough current flow on the other pins to stand in for the heater (if equipped) will result in the ECU concluding everything is fine. Presumably someone trying to work around a catalytic converter issue would be more likely than average to fall into this category.
      - asguy 5y ago
        That’s true for many early OBD-2 cars, but anything reasonably modern (e.g. 2006) correlates signals between upstream and downstream O2 sensors. Most workarounds you see on the market are patched ECU firmware to fib a scaled second O2 sensor value based on the first, so all of the diagnostic tests keep running. You’re seeing cars fail smog with these workarounds because states like California have started checking calibration IDs against the manufacturer’s listed values at the time of production.
  - hellbannedguy 5y ago
    They do check the sticker, and they will get you by. (keep all your smog checks to see if you got a working unit. Check HC's, CO, and Oxides of nitrogen against old tests. I was about to divulge a secret to poor people who want to pass smog, and can't budget a missing catalytic converters. It's a pretty good trick. The poor guys who work on their ride can probally figure it out. I will refrain though. (My biggest fear of smog, and Global warming, is the powers at be will make the poor pay for it. A two year smog is rediculious. Right now CA only exempts 1975, or earlier vechicles. Most states gave a 25 year rule. People who drive old cars are usually poor, and don't put a lot of miles on an older car. Some of those 25 year old cars are bought by collectors. Most are crushed.)
  - toast0 5y ago
    Last I looked, CA smog test for post 2000 model year cars is ODB2 only. There's a handful of 2000 and earlier models that also qualify. Anything earlier gets probed until it's old enough.
- kube-system 5y ago
  The amount of precious metals in catalytic converters vary. OEMs make high quality units that actually do a very good job of lowering emissions, because regulators are closely looking at their vehicles. The aftermarket units you see on Amazon skimp out on materials so they have lower purchase prices. They may have significantly less or sometimes zero catalytic material. While these wouldn't fool EPA inspectors hooking test equipment up to a vehicle coming right off of Ford's production line, they'll likely pass a visual inspection by your local Jiffy Lube.

sokoloff 5y ago

Used converters are not legal for sale for installation unless they’ve been individually tested for function. There are numerous catalytic converters for sale on Amazon around the $100 price point. If there’s $500 of rare metals inside, I think I’ll supplement my tech job and do a bunch of drop shipping from Amazon to a scrap metal place someplace.

mindslight 5y ago
I've heard from a mechanic that the aftermarket cats don't work particularly well, and they're basically just for fulfilling the legal requirement to repair an emissions system as designed. Presumably they skimp on the expensive catalyst. Does the CA smog test for newer cars still include an actual sensor stuck into your tailpipe, or is it all ODB2? And does the typical emissions system have any sensors past the catalytic converter?
- brianwawok 5y ago
  Many (most) states never actually hook cars up to sensors. So for most of the country, a half working converter looks right, at the cost of our air quality….
  - oasisbob 5y ago
    And, some states which used to have emission tests like Washington have discontinued them entirely, via OBD or sniffing. Justification was diminishing returns as the distribution of cars on the road has naturally changed and eliminated many problems.
    - lotsofpulp 5y ago
      Yes, people in the states without testing can just straight pipe it for $10 and half an hour of labor rather than shell out thousands to get a new cat installed. Save money and future proof yourself from further thefts.
    - Scoundreller 5y ago
      The mass testing model was always dumb because the state/emission testing vendors have test results for every car and should be able to predict which model/years need testing and which don't. Instead out of "fairness" or greed, they'd require everyone to get every car tested every X years after Y years of age when sampling would make a lot more sense.
      - mindslight 5y ago
        Erm what? The emissions and safety properties for every vehicle model are regulated at design time (in anticipation of sale). The point of periodic testing is to make sure that every instance of a design remains as-designed, and has not failed through damage, insufficient repair, or deliberately. How else would this be discovered?
- slobiwan 5y ago
  The last time I took my car in for a (California) smog check, they definitely stuck a sensor up the tailpipe. Also run the engine for fixed duration at several set speeds to get a variety of readings, on a dynomometer (a treadmill, basically) to simulate actual driving speeds.
  - kube-system 5y ago
    I think California is the only state that does this. Most other states do visual inspections or OBD-II tests.
  - dmckeon 5y ago
    Apparently Californians get a double whammy on cat thefts - a generic replacement cat converter for most states costs about $500, but the exact same replacement cat that is certified by CARB (California Air Resources Board) runs about $2k. This explains why older CA cars are more likely to be totaled out by a cat theft.
- mgarfias 5y ago
  Anything made after ‘96 has an o2 sensor downstream of the cat to verify the cat is working. If it stops working the ecu will toss a p0420 code and turn on the check engine light.
  - mindslight 5y ago
    Is it physically downstream on another part though? It's been a while since I've been under a car but I remember seeing what I thought was the O2 sensor, and it was part of the whole catalytic converter assembly. If it comes as part of the same assembly, it would be easy enough for new ones to include a fake O2 sensor.
    - mgarfias 5y ago
      It screws into either the cat, or the pipe right behind it. But it’s a separate part.
  - sokoloff 5y ago
    Those downstream checks are easily defeated in most cars. They work fine as a signal that the converter isn’t working iff you’re like most people and not trying to defeat them. If you’re trying to defeat them, a simple RC or other timer circuit on the signal pins and enough current flow on the other pins to stand in for the heater (if equipped) will result in the ECU concluding everything is fine. Presumably someone trying to work around a catalytic converter issue would be more likely than average to fall into this category.
    - asguy 5y ago
      That’s true for many early OBD-2 cars, but anything reasonably modern (e.g. 2006) correlates signals between upstream and downstream O2 sensors. Most workarounds you see on the market are patched ECU firmware to fib a scaled second O2 sensor value based on the first, so all of the diagnostic tests keep running. You’re seeing cars fail smog with these workarounds because states like California have started checking calibration IDs against the manufacturer’s listed values at the time of production.
- hellbannedguy 5y ago
  They do check the sticker, and they will get you by. (keep all your smog checks to see if you got a working unit. Check HC's, CO, and Oxides of nitrogen against old tests. I was about to divulge a secret to poor people who want to pass smog, and can't budget a missing catalytic converters. It's a pretty good trick. The poor guys who work on their ride can probally figure it out. I will refrain though. (My biggest fear of smog, and Global warming, is the powers at be will make the poor pay for it. A two year smog is rediculious. Right now CA only exempts 1975, or earlier vechicles. Most states gave a 25 year rule. People who drive old cars are usually poor, and don't put a lot of miles on an older car. Some of those 25 year old cars are bought by collectors. Most are crushed.)
- toast0 5y ago
  Last I looked, CA smog test for post 2000 model year cars is ODB2 only. There's a handful of 2000 and earlier models that also qualify. Anything earlier gets probed until it's old enough.
kube-system 5y ago
The amount of precious metals in catalytic converters vary. OEMs make high quality units that actually do a very good job of lowering emissions, because regulators are closely looking at their vehicles. The aftermarket units you see on Amazon skimp out on materials so they have lower purchase prices. They may have significantly less or sometimes zero catalytic material. While these wouldn't fool EPA inspectors hooking test equipment up to a vehicle coming right off of Ford's production line, they'll likely pass a visual inspection by your local Jiffy Lube.