0430 Cel

[ASpec818]

Had a CEL popup recently and it reads catalytic converter system efficiency below threshold b2. We reset it via an obdII reader and reappeared about 40 miles later. Before getting a new cat, I want to try some things. I just dumped some Techron cleaner and refilled with gas today. Was wondering when I should reset the light (after burning the tank of gas or now) and if I should disconnect the battery instead of a reader reset?

[paulv]

The aft O2 sensor measures the ability of the cat to store oxygen. Just because you got this code, it doesn't necessarily mean that the cat has failed. Resetting the code doesn't make the problem go away. For a first step, I would swap the two aft O2 sensors to see if the problem moves to the other bank -- while doing this, inspect the wiring for any problems (if it was the O2 sensor, then you'd get a P0420 DTC). Also, check the exhaust around the cat to see if there's any small holes as these would let in air and skew the O2 readings.

Please provide year/mileage on car.

Regards,
paul...

[Perfectlap]

I just got the same code after installing a Fabspeed exhaust (full).
I also think I have a wiring harness issue as well since I've been repeatedly getting the same driver's side pre-cat CEL even after swapping out all the 02 sensor with new Bosch units. Anyone ever replace this sort of wiring?

[Jager]

Is P0430 the only alarm code you have? Others have cleared that alarm by replacing the MAF sensor. So the problem can be way upstream of the exhaust system. CAT replacement is the last thing you want to do.

[ASpec818]

Originally Posted by Jager

Is P0430 the only alarm code you have? Others have cleared that alarm by replacing the MAF sensor. So the problem can be way upstream of the exhaust system. CAT replacement is the last thing you want to do.

Yes that's the only code pulling on the reader. I'm not familiar with the Boxster emissions system and do not have experienced knowledge. How can I check the maf sensor? Should I try cleaning the sensor?

And for the o2 sensor swap, is this fairly straight forward?

[Jager]

Yes you can clean the MAF sensor, you will need a tamper resistant Torx bit (T-10) see picture below.

You can try swapping the O2 sensors but that might not tell you much, I would expect the same alarm after swapping.

Catalytic converters are very expensive and rarely are they the issue. Normally it’s a problem upstream (sensors, vacuum leaks).

[ASpec818]

Originally Posted by paulv

The aft O2 sensor measures the ability of the cat to store oxygen. Just because you got this code, it doesn't necessarily mean that the cat has failed. Resetting the code doesn't make the problem go away. For a first step, I would swap the two aft O2 sensors to see if the problem moves to the other bank -- while doing this, inspect the wiring for any problems (if it was the O2 sensor, then you'd get a P0420 DTC). Also, check the exhaust around the cat to see if there's any small holes as these would let in air and skew the O2 readings.

Please provide year/mileage on car.

Regards,
paul...

After cleaning the MAF and resetting the ecu, the light is back on after 50 miles. Seems the next step is the check the o2 sensors. I understand there are 4 sensors. Which is the suspect sensor? Is there a link I can follow to check the sensor?


I have a 2000 Boxster S w/ 72k miles

[Jager]

Check the seal on your gas cap, it can also throw a 0430 alarm code (although my experience there were also a 0410 and 1411 alarms). If the gas cap seal has cracks you will have a vacuum leak. You could also have a bad MAF sensor.

[ASpec818]

Just checked gas cap and there aren't many cracks. I'm going to be swapping the o2 sensors in hopes of pinpointing a possible sensor failure once I get my durametric software in. I understand there are 2 precat o2 sensors, and 2 post cat o2 sensors. Which o2 sensors should I swap?

Also, is bank 2 the driver's side?

[Jager]

Yes bank 2 is on the driver's side.

Many things can cause the P0430 DTC; bad MAF sensor, bad AOS bellows, low fuel pressure etc. One of the O2 sensors could also have a loose connection, swapping could reveal something. Have you opened the oil fill cap while the car is running? Does the engine idle go up or down? Is the cap hard to take off?