Question about 2003 Chevrolet S-10
Hello and welcome. the trouble code P0420 means,In order to maintain low emissions of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx), the engine controls system uses a 3-way catalytic converter (TWC). The catalyst within the TWC promotes a chemical reaction, which oxidizes the HC and CO that are present in the exhaust gas. This reaction converts these chemicals into harmless water vapor and carbon dioxide. The catalyst also reduces the NOx which converts into nitrogen. The powertrain control module (PCM) monitors this process using heated oxygen sensor (HO2S) bank 1 sensor 2, which is located in the exhaust stream past the TWC. The HO2S bank 1 sensor 2 produces an output signal which indicates the oxygen storage capacity of the catalyst. This determines the catalysts ability to effectively convert the exhaust emissions. If the catalyst is functioning correctly, the bank 1 of the HO2S 2 signal will be far less active than the signal that is produced by bank 1 of the HO2S 1. This indicates that the TWC oxygen storage capacity is below an acceptable threshold. in simple terms, the cat. coverter is bad and will need to be replaced. the cat. converter simply is not removing the excessive emission is it is designed to do
Posted on Aug 06, 2010
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Posted on Jan 02, 2017
Basically, your on board computer is telling you your catalytic
converter is not working properly. As you know, you have a sensor in
front and in back of the converter. The computer compares the waveforms
from each sensor. If the sensor waveform before and after the cat are
the same, then the cat is not working. You should have an analysis of
the waveforms at each sensor analyzed at a shop and, if they are the
same, the dealer should replace the cat if it is still under warranty. Most common would be the O2 sensor after the Catalytic converter has failed and will need to be replaced. It takes about 15 min to replace and any muffler shop can replace the O2 sensor for you.
Posted on Dec 09, 2009
SOURCE: p0420 code on my 2003 chevy s10
CATALYST SYSTEM LOW EFFICIENCY ,MEANING THE CAT MONITOR SENSOR WAS NOT SENDING THE CORRECT SIGNAL TO THE ECM MOST LIKELY CAUSE IS A FAULTY CAT MONITOR SENSOR OR FAULTY CATALYTIC CONVERTOR.
Posted on Aug 06, 2010
SOURCE: code reading p0420 on '99
there are a couple of things to consider here. That code indicates that the O2 sensor behind the cat is not functioning like the engine computer expects-either the cat itself is not functioning properly or you may have an exhaust leak, or the heater circuit in the O2 sensor is faulty. The cat should get up to 600 degrees and it burns unburned fuel before ti gets to the 2ed O2 sensor-if it cannot do this, the CEL comes on and you have a P0420. Before replacing the cat, clear the code and see if it comes back-if it does, you might try first replacing the O2 sensor. If that doesn't work, get a 'oil fouler' spark plug adapter and install the O2 sensor in it, then install both into the exhaust-this 'shields' the tip of the O2 sensor and slows it down, fooling the engine computer into seeing it switching slowly, as it is supposed to do. Your only other choice is to replace the cat, and an aftermarket cat is much less than an OEM unit.
By the way, if you have burnt valves, a P0420 is the least of your worries.
Posted on Apr 01, 2011
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