0430 Cel

[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?

[ASpec818]

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

[Jager]

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]

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]

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]

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.