Contour Enthusiasts Group Archives Forums General Troubleshooting P0430 maybe fixed without replacing cat?

I manually cleaned my intake manifolds and injectors. My lean codes and my misfire codes are gone, but I still have a PO420. I have 3 weeks left until I have to go retest at the emissions site. I failed in February based off of my OBDII. New O2 Sensor(s)?

Replace the upstream O2 sensors, not the downstream ones. Leave the downstream ones alone.

To keep the P0430 code from coming back, you want the upstream O2 sensor to switch faster than the downstream sensor.

O2 sensors start switching slower as they age, so it would stand to reason that replacing the upstream O2 sensors and leaving the downstream ones alone might change the upstream/downstream switch ratio enough to make the P0430 code go away. Might being the key word. I can't promise anything.

Also, I talked with my mechanic about how the B12 Chemtoool seemingly fixed the cat, and he mentioned that carburetor cleaner heats the cats up, which might be the sort of "kick start" they need to start working efficiently.

So before you replace those cats, might I suggest spraying some B12 Chemtool or other carb/throttle body cleaner into the intake with the engine running? When I did mine I sprayed the cleaner for 10 seconds while revving the engine, let the engine idle for 10 seconds without spraying any cleaner in, and did this until I'd used about half of a 16oz can.

If you use B12 Chemtool, it's got a powerful enough stream that you can spray it in from a foot away. Most of the throttle body cleaners have a weak stream and it's hard to spray them in effectively without completely removing the air duct.

What if you have the B12 but its not in a spray can, its a can you pour with. Is there any way I could use it?

You could try this:

Cleaning intake manifolds without removing them

This procedure basically tells you how to suck the cleaner into the intake manifold via a hose.

It should produce similar results to using spray-in cleaner.

Like using a spray-in cleaner, it will clean more than just the intake manifolds, and will have the same effects on the cat.

By the way, I've never had to change the plugs after doing this, nor have I changed the oil. As far as the plugs go, I've never had one foul out on me, and as far as the oil goes, I figure that the cleaner will evaporate (I help it along by taking the car on a drive at highway speeds after doing this) and be dealt with by the PCV valve.

99,900 miles with no recurrance of the P0430 code.

101,800 miles with no recurrence of the P0430 code. I did have a false scare though--CEL came on and I scanned it, was some evaporative emissions code. (P1443 I think). I cleared it it and it never came back.

Thanks for the updates Brian, need to try this on my car...

Replaced both upstream O2 sensors today (Hands are all cut up too!), used cleaner like you said... before the swap, and also added a can of B12 to my fuel.

No check-engine lights so far after about 60 mile combined city/highway.

I will report more results after more milage.

Car has 103K miles, had original O2s, and P0430 codes..

thanks Brian!