Need desperate help with trouble codes regarding emissions!

Asked by Jun 07, 2016 at 06:54 PM about the 2000 Chevrolet Silverado 1500 LS Ext Cab Short Bed 4WD

Question type: Maintenance & Repair

I need some help with some trouble codes.  I have a 2000 Chevy Silverado
1500, 4x4, with 5.3l V-8 engine.  Over the past week, I've had the following
trouble codes: P0300 and P0137 (can't remember exactly, but had to do with
post cat, driver's side).  I replaced the O2 sensor and cleared the codes, but
the P0300 returned.  I cleared the code again the next day, then got code
P0307.  Spark plugs were only 1 1/2 years old, so I replaced all the spark
plug wires.  

Code remained, so I then went ahead and replaced the #7 spark plug, and
swapped the #7 coil with the #5, then cleared the code.  Trouble code did not
return, and did not follow to #5 cylinder, but I then got the code P0430,
Catalyst system efficiency below threshold, bank 2.  

I took the truck to a certified mechanic, who did a much better diagnostic test
that what I have at home.  Mechanic stated the CAT on passenger side is
working as it's supposed to and suggested that the O2 sensors need to be
replaced.  So I replaced the remaining 3 O2 sensors, cleared the code.  But
of course the check engine light came back on and it;s the same P0430

Any suggestions would be greatly appreciated.

3 Answers


P0430 CHEVROLET - Catalyst System Low Efficiency Bank 2... Possible causes - Three way catalyst converter Bank 2 - Exhaust tube - Intake air leaks - Fuel injectors may be faulty - Fuel injector leaks - Spark plugs may be faulty - Improper ignition timing - Powertrain Control Module (PCM)... As the code description implies the P0430 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0430 code is combined with other codes, try fixing the other codes first.. If a condition exists which causes the Powertrain Control Module (PCM) to detect excessive Bank 2 HO2S #2 activity outside of an acceptable range for an extended period of time, the PCM will set the P0420 code. This indicates that the three-way catalytic converters oxygen storage capacity is below a threshold considered acceptable... P0430 Chevrolet Description.... In order to maintain a reasonably low emissions of Hydrocarbons (HC), Carbon Monoxide (CO), and Oxides of Nitrogen (NOx), the engine controls system uses a three-way catalytic converter. The catalyst within the converter promotes a chemical reaction which oxidizes the HC and CO present in the exhaust gas. This reaction converts them into harmless water vapor and Carbon Dioxide. The catalyst also reduces NOx, converting it to Nitrogen. The Powertrain Control Module (PCM) monitors this process using Bank 2 HO2S #2. Bank 2 HO2S #2, located in the exhaust stream past the three-way catalytic converter, produces an output signal which indicates the oxygen storage capacity of the catalyst. This determines the catalysts ability to convert exhaust emissions effectively. If the catalyst is functioning correctly, the Bank 2 HO2S #2 signal will be far less active than that produced by Bank 2 HO2S #1.

Thanks Rowefast. All of the troubles related to the other codes have been fixed, as those codes have not returned. I'll check everything else as you've recommended. Keep you posted if that fixes everything for me.


Sounds good! Have a good one...

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