99 tahoe still throwing P0430 code

I have been battling this for some time now. I have replaced the cat, and both O2 sensors on bank 2 and still getting the code. It comes on if a drive a long distance, get on it, or just start it up. I replaced the cat back in '07. If that is the problem, is it still under warranty? I did notice today that there is a small puddle of water under the second O2 sensor. Could this small leak be causing the problem also?
Thanks!

Was it a good cat or a muffler shop el cheapo?

http://www.troublecodes.net/articles/catfailure/

Cat code takes a lot of proper testing to find the cause of the problem.
Has it been tested out good?

Many times a engine missing or running rich can give cat codes.
Somehave VCM/PCM reprogram for cat codes.
Have you check the TSB's for that?

How is engine running and tune up end?



DTC P0420, P0421, and P0430 & P0431: Check Possible Cause Of Misfire DTC P0420 and P0421 indicate bank one catalyst system efficiency is minimum requirement. DTC P0430 and P0430 indicate bank 2-catalyst system efficiency is minimum requirement. Possible causes are as follows: Use of leaded fuel. Oil contamination. Cylinder misfire. Fuel pressure too high. HO2S sensor improperly connected. Damaged exhaust system component. Faulty ECT sensor. Faulty HO2S. Ensure ignition timing is correct. Retrieve all Continuous Memory DTCs. If misfire code is not present, go to next step. If misfire code is present, isolate cylinder and repair as necessary. Check HO2S Monitor DTCs If DTCs P0136, P0138, P0140, P0141, P0156, P0158, P0160, or P0161 were present in step 1), service as necessary before continuing. If none of these codes are present in step 1), go to next step. Check ECT Sensor DTCs If DTCs P0117, P0118, P0125 or P1117 were present in step 1), service as necessary before continuing. If none of these codes are present in step 1), go to next step. If any codes except P0420, P0421, P0430 and/or P0430 were present in step 1), service as necessary before continuing. If no codes except P0420 and/or P0430 were present in step 1), go to next step. Check Rear HO2S Wiring Harness Turn ignition off. Ensure HO2S wiring harness is correctly routed and connectors are tight. Repair or replace as necessary. If wiring harness and connectors are okay, go to next step. Check Fuel Pressure Turn ignition off. Release fuel pressure. Install fuel pressure gauge. Start engine and allow to idle. Note fuel pressure gauge reading. Increase engine speed to 2500 RPM and maintain for one minute. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to CIRCUIT TEST HC. Check For Exhaust System Leaks If exhaust system leaks, it may cause catalyst monitor efficiency test to fail. Inspect exhaust system for cracks, loose connections or punctures. Repair or replace as necessary. If exhaust system is okay, go to next step. Check For Exhaust System Restrictions Inspect exhaust system for collapsed areas, dents or excessive bending. Repair or replace as necessary. If exhaust system is okay, go to next step. Check Manifold Vacuum Install tachometer. Connect vacuum gauge to intake manifold vacuum source. Start engine and raise engine speed to 2000 RPM. Manifold vacuum should rise to more than 16 in. Hg. If manifold vacuum is okay, go to next step. If manifold vacuum is low, go to step 11). Leave tachometer and vacuum gauge connected. Start engine and raise engine speed to 2000 RPM. On a non- restricted system, manifold vacuum should quickly rise to normal range as increased RPM is maintained. On a restricted system, manifold vacuum will slowly rise to normal range as increased RPM is maintained. If manifold vacuum is okay, no indication of exhaust leak or restriction has been detected and testing is complete. If manifold vacuum is low or slow to respond, go to next step. Leave tachometer and vacuum gauge connected. Remove exhaust pipe from exhaust manifold. Start engine and raise engine speed to 2000 RPM. If manifold vacuum is now okay, fault is downstream from exhaust manifold. Reconnect exhaust pipe to exhaust manifold and go to next step. If manifold vacuum is still low or slow to respond, fault is in exhaust manifold or intake manifold gasket. Repair or replace as necessary and repeat QUICK TEST. Leave tachometer and vacuum gauge connected. Disconnect muffler/tailpipe assembly from rear of catalytic converter. Start engine and raise engine speed to 2000 RPM. If manifold vacuum is now okay, fault is in muffler/tailpipe assembly. Repair or replace as necessary and test-drive vehicle to verify elimination of symptom. If manifold vacuum is still not okay, fault is in catalytic converter. Repair or replace as necessary. Check tailpipe/muffler assembly for debris from catalytic converter. Test drive vehicle to verify elimination of symptom.

It was not an el cheapo cat but I don't believe it was GM either. If I take it to a shop, with the correct scanner/reader, can they pinpoint the failure exactly?

As posted it takes a lot of testing and a good engine capable scanner to find the problem.

A good repair shop would be best.

It was not an el cheapo cat but I don't believe it was GM either. If I take it to a shop, with the correct scanner/reader, can they pinpoint the failure exactly?

swap the o2 sensors driverside /passenger side...inspect the wires connectors no splices or hack wire jobs allowed this throws off the voltage..make sure no wires are burnt damaged...

see if it changes to the other side..
if not this is usually a bad cat converter...as stated these aftermarket converters are not the best in some cases..

what engine/ how many miles on first converter replacement ?

The fact that you have exhaust condensation dripping from the o2 sensor area could mean it's not sealed properly. As mentioned, swap the two downstream sensors and see what happens.

Are you sure you didn't blow your new cat on bank 2?
Have a local muffler shop compare both banks with a back pressure test.
One backfire could damage a catalytic converter.