Re: It is the 1st converter, the pre-converter. If you look at the exhaust system you can seen an O2...

My 2001 Boxster will occasionally throw a 0430 code. It has never thrown any other code and I've checked out the graphs from the 02sensors and they appear to be working fine. My question is which driver's side catalytic converter is it?

The 97 - 99 cars have one catalytic converter right before the muffler and 02 sensors on either side of it. From 2000 on Porsche added a catalytic converter on the exhaust manifold with 02 sensors on either side of it and removed sensors from the catalytic converter closer to the muffler. I've always been told to replace the converter next the the muffler, but I don't understand how that would make a difference when the sensors are on the exhaust manifold. Am I crazy? It seems like the sensor should be before the first converter and after the second one.

As the manual says "In the case of a catalytic converter fault in the Boxster (2.7l and 3.2l), only the pre-catalytic converter is to be
replaced." As I'm thinking of it how would the sensor know of any issue past where it is in the exhaust stream?

But my big question is why should the cat be clogged? Any mods? Any history of other faults (AOS?) that would allow unburned gas or excess soot to be in the cat for processing? How many miles? Most go a long long way unless there has been some problem that makes for abnormal input to the cats.

Quote
racyclist
My 2001 Boxster will occasionally throw a 0430 code. It has never thrown any other code and I've checked out the graphs from the 02sensors and they appear to be working fine. My question is which driver's side catalytic converter is it?

The 97 - 99 cars have one catalytic converter right before the muffler and 02 sensors on either side of it. From 2000 on Porsche added a catalytic converter on the exhaust manifold with 02 sensors on either side of it and removed sensors from the catalytic converter closer to the muffler. I've always been told to replace the converter next the the muffler, but I don't understand how that would make a difference when the sensors are on the exhaust manifold. Am I crazy? It seems like the sensor should be before the first converter and after the second one.

sensor just ahead of this converter and one immediately after it. The O2 sensor after the converter is primarily used to monitor the efficiency of that converter. (The larger converters further down the exhaust system are not monitored.)

The #2 converter might be bad but there is no way to know this if the 1st converter is bad. The 1st converter (if bad) must be replaced (if the problem is not an aging O2 sensor or an exhaust leak or something other than the converter) and then the #2 converter's performance verified with an exhaust gas analysis (smog test using an exhaust pipe probe (sniffer) to verify exhaust gas emissions are within acceptable ranges.

Sincerely,

MarcW.

Thats for the replies, I almost made a costly mistake buying the wrong part.

It makes sense that the first converter is the one being tested, but it seems backward that Porsche doesn't test the bigger cat instead. In my state smog is OBDII testing only so I guess I'll never know if the second cat is bad. I suppose I shouldn't complain too much the smaller cat is cheaper at autoatlanta.

Mike, I bought the car without doing a PPI. It was so shiny, how could I go wrong? I immediately took it in for service and found out the AOS was "definitely bad". The car has 87k miles. I bought it just outside of emissions warranty at 82k.

Quote
racyclist
Thats for the replies, I almost made a costly mistake buying the wrong part.

It makes sense that the first converter is the one being tested, but it seems backward that Porsche doesn't test the bigger cat instead. In my state smog is OBDII testing only so I guess I'll never know if the second cat is bad. I suppose I shouldn't complain too much the smaller cat is cheaper at autoatlanta.

Mike, I bought the car without doing a PPI. It was so shiny, how could I go wrong? I immediately took it in for service and found out the AOS was "definitely bad". The car has 87k miles. I bought it just outside of emissions warranty at 82k.

is that if the 1st converter is working ok the 2nd converter is too.

To monitor the #2 converter would require additional sensors, more complex exhaust system, more wiring and longer wiring and this adds weight and cost to the car. Dollars, even pennies matter even with the product costs $45K or more...

If the engine is running ok, if the #1 converters are working ok, the 2nd converters are ok. You can't know they're bad unless you subject the engine to emissions testing. Here in CA this is done every so often when tail pipe emissions are measured.

I might add it may be that even though the #1 converter on your car is not working ok that the #2 converter may be working just fine and is cleaning up the exhaust that #1 converter is letting go through without processing. However, at least here in CA, if the check engine light is on (or too many readiness monitors are set to 'incomplete'), it doesn't matter if the tail pipe emissions are within acceptable ranges. The car will fail the test.

The intent is to give the driver adequate warning something is wrong in the emissions area of the engine/car so it can be addressed before the engine really begins to emit gross amount of pollution.

Sincerely,

MarcW.