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P0430 Cat efficiency code, Help

I know by having the computer scanned that this code is pass side cat efficiency issue.. I hear its most likely the o2 sensor, possibly the cat itself. What are the chances its the cat.. If it wasnt for the cost factor Id just replace all 4 o2s and be done with it. Im also worried it may not be the O2 and be the cat itself. I heard to test the o2 sensors you get the vechicle up to op temp, and check milivoltage on the sensor wires and look for fluctuations between.02 and .08 I believe? There are 4 wires coming from the O2 which 2 of the 4 do I probe...... Also do I disconnect the sensor and probe in the harness or should I pierce the wire while its connected. Im hitting this project tomarrow morning along with a water pump so quick replys are appreciated. Its a 98 Tahoe 5.7. Thanks Tony

Reply to
Rokihora
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The truck uses the precat 02 and postcat 02 sensors to test the efficiency of the cataylist at operating temp. When the PCM compares the readings from both the precat and postcat 02s it uses that to determine how well the cat is converting the gases. When the difference between the two isn't all that much it will set that code. The PCM has different codes that will set for 02 performance or O2 circuit failures. PCM monitors the O2s constantly. If you don't have an O2 code look elsewhere. If the O2 was the problem it would most likely set an O2 code. 19 out of 20 I see usually end up getting a new cat. The bigger issue is why did the cat go bad? If thats not fixed then the new one is going to go south in a hurry also. You burning oil? Running rich? Burning coolant? Any exhaust leaks precat? Any other drivability codes set? Hows the fuel trim? Engine miss? Could be any number of things. Oh by the way if it has less than 100,000 miles on it the cat will still be covered under factory warranty. I think its a 10 year 100,000 mile warranty but the time may be shorter, might be a 6 year, I'm not sure. Call up to the dealer, and see if your still covered, trust me, cats aren't cheap. Why pay for it yourself when there is a chance that you can get it done for free. Piercing wires for testing is never a good idea especially ones that are in the elements. Just asking for trouble. The proper way to diagnose an O2 is with a scan tool and study the waveform.

Reply to
Jay

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I think its a 10 year 100,000 mile warranty but the time may be shorter, might be a 6 year,

I'm not sure.

Call up to the dealer, and see if your still covered, trust me, cats aren't cheap.

Why pay for it yourself when there is a chance that you can get it done for free.

Reply to
Marsh Monster

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