Code P0430

Cat Efficiency Below Thresholds Bank 2
?

I replaced pre cat o2's.....what next?

1998 Tahoe, A/T, 105,000 tune up good...............

Lar

Which side is Bank 2?

Which side is Bank 2?

Bank 1 is the side with Cylinder 1 (drivers side)
Bank 2 is the side with Cylinder 2 (passenger side)

//2000CAYukon

Swap the post-cat O2 sensors, bank 2 to 1, vice-versa. If the code follows the sensor, the sensor may be bad. If not, the cat is bad. With over 100,000
miles, I'm betting on the cat.

Swap the post-cat O2 sensors, bank 2 to 1, vice-versa. If the code follows the sensor, the sensor may be bad. If not, the cat is bad. With over 100,000
miles, I'm betting on the cat. Remember, the left cat is serving the right engine bank.

Thanks, I'll try switching the post cat O2's and see what happened.

the cat may be shot. at 88,000 I had the proverbial intake gasket leak and that side consumed some H2O for about 20 miles to shop...........code has been on since......no faul smell in exhaust. the pre-cat O2 on Bank 2 had a brown deposit on the upstream side of the tip..........cat most likely has same issue.

Lar

Rockauto.com has a pretty good price for these cats-goes from the exhaust manifolds to the flange upstream of the muffler for under $300.

http://www.troublecodes.net/articles/catfailure/
Aso some more info. Good Luck MT
DTC P0420, P0421, P0430 & P0431: Check Possible Cause Of Misfire DTC P0420 and P0421 indicates bank one catalyst system efficiency is minimum requirement. DTC P0430 and P0430 indicates 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(s) is not present, go to next step. If misfire code(s) 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. Ć 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 engineand 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.

Sounds like I have a weekend trouble shooting party upcoming.

thanks

lar

MT-2500

can you help with the acronym ECT Electronic Coolant Temp Sensor?

MT-2500

can you help with the acronym ECT Electronic Coolant Temp Sensor?

What kind of help are you needing with it
Is the acronym a add on aftermarket gauge or sensor?
I am a little lost on it.
How did you come out on the cat code?
MT