0430 Cel - 986 Forum - The Community for Porsche Boxster & Cayman Owners

ASpec818 · 06-29-2011, 10:35 PM

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 · 06-30-2011, 05:11 AM

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 · 06-30-2011, 06:58 AM

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 · 06-30-2011, 06:18 PM

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 · 06-30-2011, 06:24 PM

Quote:

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 · 06-30-2011, 06:45 PM

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 · 06-30-2011, 08:35 PM

OK i just removed and cleaned the MAF sensor along with disconnecting battery. Will report back if/when CEL reappears.

ASpec818 · 07-10-2011, 02:20 PM

Quote:

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 · 07-10-2011, 05:29 PM

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 · 07-11-2011, 09:26 PM

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 · 07-12-2011, 06:55 PM

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?

ASpec818 · 07-12-2011, 09:34 PM

do i swap the pre cat or post cat o2 sensors, or both? i'll try the sensors next

Jager · 07-13-2011, 06:44 PM

Have you checked your AOS by removing the oil fill cap while the car is running? What did the idle do?

With the P0430 alarm swapping the O2 sensors is a coin toss... I personally would start with the pre cat sensors first.

So how many cracks did you have on your gas cap seal?

Topless · 07-14-2011, 06:33 AM

Ok, let's analyze this a bit. You have a 2000 Box with 72K miles and a CEL showing a P0430 code. This code indicates a failed cat on the left side of the car. Checking the MAF, AOS and gas cap are always good maintenance checks but today they are probably unrelated. No mixture codes at all. You don't have a mixture/air leak problem you have a cat/sensor problem.

Three choices:
1. Add a bottle of Techron fuel additive and go for a spirited drive. You might get lucky and burn off whatever was causing cat inefficiency.
2. Replace the cat (rear-left side). Most likely fix.
3. Replace the aft sensor and cross your fingers that it was not reporting properly.

Here is a good description of how O2 sensors work:
http://sites.google.com/site/mikefocke2/oxygensensors

Good luck!

Jager · 07-14-2011, 07:16 PM

Topless,
I agree with you on what the trouble code indicates but I replaced all of my O2 sensors when I had 210,000 on my 2001 (bad AOS damaged them). Drove the car for about 2000 miles with no alarms, then got a P0430, P0410, and P1411 in memory with no CEL (I check the system occasionally with my Durametric). I ended up replacing my gas cap (way past due/real bad shape/original) then cleared the alarms and have not seen those trouble codes since. Was the P0430 alarm just coincidental? Did the bad gas cap create the P0430 alarm? BTW I have never replaced my catalytic convers, they are original.

Talking to one of the local mechanics they have had some success running a cleaner through the induction system that helps clean catalytic converters so your suggestion of adding some Techron to the fuel might do the trick.

Topless · 07-15-2011, 06:53 AM

Quote:

Originally Posted by Jager

Topless,
I agree with you on what the trouble code indicates but I replaced all of my O2 sensors when I had 210,000 on my 2001 (bad AOS damaged them). Drove the car for about 2000 miles with no alarms, then got a P0430, P0410, and P1411 in memory with no CEL (I check the system occasionally with my Durametric). I ended up replacing my gas cap (way past due/real bad shape/original) then cleared the alarms and have not seen those trouble codes since. Was the P0430 alarm just coincidental? Did the bad gas cap create the P0430 alarm? BTW I have never replaced my catalytic convers, they are original.

Talking to one of the local mechanics they have had some success running a cleaner through the induction system that helps clean catalytic converters so your suggestion of adding some Techron to the fuel might do the trick.

A bad AOS can definitely foul your cats if you continue to drive the car due to excessive oil feeding the motor. Adding Techron might?? clear it up. A bad AOS will also cause mixture codes to come up (car will run lean). Since the OP said his AOS passed the "pull oil fill cap" test and had no mixture codes we can eliminate the AOS as a likely problem. A failed gas cap, bad AOS, intake air leak, and bad MAF will result in a CEL with mixture codes from the primary o2 sensors. Since the OP had no error codes from the primary o2 sensors we can eliminate these as a likely possibility. Just a basic process of elimination.

ASpec818 · 07-15-2011, 06:35 PM

Here's an update. I got my durametric in today and checked for the fault codes. P1128 and P1130 codes popped up as well. They are: Oxygen sensing adaptation idle range bank 1 and Oxygen sensing adaptation idle range bank 2

I've been reading if these two codes pop up together it's likely it's the maf sensor?I hope I didn't screw anything up as I've cleaned the sensor recently. I'm not sure if the codes were there prior to cleaning, as the mechanic used a basic obd2 reader and only pulled the P0430 code.

The car also seems to run fine.

Jager · 07-15-2011, 09:57 PM

Glad to see you have a Durametric, now you can really get into troubleshooting the vehicle. I would clear the alarms and see if they come back in a few days, maybe you triggered them when you opened your oil fill cap doing the AOS test?

I've had those same alarms... They went away after I replaced my AOS (it was definitely bad) and then replaced all my O2 sensors (damaged from driving with a bad AOS too long).

I would take Topless suggestion of adding Techron additive to the fuel tank and taking it for a brisk drive.

ASpec818 · 08-06-2011, 04:04 PM

As an update, the CEL has stayed off for about 70 miles now (I barely drive) and I passed smog today with flying colors. All I did was pour a bottle of techron cleaner, clean the maf sensor, and replace some leaking spark plug tubes. I'm wondering if the oil from my leaking spark plug tubes caused incorrect o2 sensor readings.

Also for some reason, even though my Durametrics still showed that the secondary air system was not ready, I didn't fail any functional tests during the smog check.