Question about 1999 Chevrolet Blazer

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Code reading p0420 on '99 chevy s10 blazer, low catalyst threshold. Is this a bad catalytic converter or burned valves?

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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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Po421


po421 catalytic converter code [warm up catalyst efficiency below threshold bank 1] means the o2 sensor is detecting low oxygen in exhaust problem can be cat conv going bad---o2 sensor faulty-and or bad spark plug ....as to the p0441 evap system[-evap emissions control system incorrect purge flow ] this is a system code meaning any part of the evap can have problem will need to check the fuel lines vapor lines for damage or breaks-check purge valve -purge valve solenoid- canister- and vacuum lines

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P0420 code on my 2003 chevy s10


please go to the provide link for diagnosis of this code,but the bottom line here is the catalytic converter may be worn out

http://www.p0420.com/

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The only fault code on 2001 kia sephia is P0422, catylist threshold low.... car ran for 2 weeks fine after new fuel pump, and then just died like first time.... 126 thousnd miles and plenty of fuel, fuel...


P0422 - Catalyst below threshold.

Catalytic converter is clogged or out of medium.

Replace it.


ACTUAL DIAGNOSTIC:

Fault Code Definition
Code P0422 indicates that the Bank 1 Main Catalytic Converter's emissions efficiency has fallen below the minimum allowable limit. This threshold is tracked by a Catalyst Monitoring Oxygen Sensor located on or near the outlet of the Catalytic Converter.

Symptoms

* Check Engine Light will illuminate
* In many cases, no abnormal symptoms may be noticed

Common Problems That Trigger the P0422 Code

* Defective Catalytic Converter
* Engine misfires have damaged the Catalytic Converter
* Internal engine damage resulting in high oil consumption and/or a leaking Head gasket has damaged the Catalytic Converter

Common Misdiagnoses

* Oxygen Sensors are replaced when the real problem is a damaged Catalyst
* Catalyst is replaced when the real problem is internal engine damage, which is producing elevated emissions levels
* Catalyst is replaced when a misfiring engine is the real problem



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Trouble codes


You mean P0420? You need a new cat converter. The "Mechanic" couldnt tell you that?

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Code PO42O and PO43O ? Anyone know what they


The meaning of: P0420 Catalyst System Efficiency Below Threshold on Bank 1 P0430 Catalyst System Efficiency Below Threshold on Bank 2

Basically the Oxygen sensors ( one before and one after the catalytic converter ) have abnormal readings from the exhaust. Further diagnosing will need to be done by a mechanic to find the source of the problem. The possibilities could be the O2 sensors themselves, a leak in the exhaust manifold, a bad catalytic converter, and etc.

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1 Answer

1996 VW Jetta has an engine code of P1586 Engine


P0422 - Catalyst below threshold.

Catalytic converter is clogged or out of medium.

Replace it.


ACTUAL DIAGNOSTIC:

Fault Code Definition
Code P0422 indicates that the Bank 1 Main Catalytic Converter's emissions efficiency has fallen below the minimum allowable limit. This threshold is tracked by a Catalyst Monitoring Oxygen Sensor located on or near the outlet of the Catalytic Converter.

Symptoms

* Check Engine Light will illuminate
* In many cases, no abnormal symptoms may be noticed

Common Problems That Trigger the P0422 Code

* Defective Catalytic Converter
* Engine misfires have damaged the Catalytic Converter
* Internal engine damage resulting in high oil consumption and/or a leaking Head gasket has damaged the Catalytic Converter

Common Misdiagnoses

* Oxygen Sensors are replaced when the real problem is a damaged Catalyst
* Catalyst is replaced when the real problem is internal engine damage, which is producing elevated emissions levels
* Catalyst is replaced when a misfiring engine is the real problem



Thanks for using FixYa - a 4 THUMBS rating is appreciated for answering your FREE question.#$%^&

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Trouble code


DTC P0420 Catalyst System Low Efficiency Bank 1

You will find a bad O2 Sensor behind the converter or a bad catalytic converter on the bank 1 side of the exhaust manifold. This is the one on the drivers side.

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Jetta temp sensor related to other codes?


P0422 - Catalyst below threshold.

Catalytic converter is clogged or out of medium.

Replace it.


ACTUAL DIAGNOSTIC:

Fault Code Definition
Code P0422 indicates that the Bank 1 Main Catalytic Converter's emissions efficiency has fallen below the minimum allowable limit. This threshold is tracked by a Catalyst Monitoring Oxygen Sensor located on or near the outlet of the Catalytic Converter.

Symptoms

* Check Engine Light will illuminate
* In many cases, no abnormal symptoms may be noticed

Common Problems That Trigger the P0422 Code

* Defective Catalytic Converter
* Engine misfires have damaged the Catalytic Converter
* Internal engine damage resulting in high oil consumption and/or a leaking Head gasket has damaged the Catalytic Converter

Common Misdiagnoses

* Oxygen Sensors are replaced when the real problem is a damaged Catalyst
* Catalyst is replaced when the real problem is internal engine damage, which is producing elevated emissions levels
* Catalyst is replaced when a misfiring engine is the real problem



Thanks for using FixYa - a 4 THUMBS rating is appreciated for answering your FREE question.!@##

Jul 11, 2009 | 1999 Volkswagen New Jetta

2 Answers

Chevy Blazer P0303 and P0420


Most probably and if a cat is not flowing proper is causes back preasure that can result in sticking or burned vavles,mechanic not nice by saying ignore the cat effiency code p0420.Can ussually have cat replaced at aftermarket muffler shop for approx. $200 cheaper than valve job or excessive fuel that you have used and damage that may occur to your engine.

Jun 16, 2009 | 1999 Chevrolet Blazer

1 Answer

1999 beetle P0422 which O2 is bad the o2 before the cat or after


P0422 - Catalyst below threshold.

Catalytic converter is clogged or out of medium.

Replace it.


ACTUAL DIAGNOSTIC:

Fault Code Definition
Code P0422 indicates that the Bank 1 Main Catalytic Converter's emissions efficiency has fallen below the minimum allowable limit. This threshold is tracked by a Catalyst Monitoring Oxygen Sensor located on or near the outlet of the Catalytic Converter.

Symptoms

* Check Engine Light will illuminate
* In many cases, no abnormal symptoms may be noticed

Common Problems That Trigger the P0422 Code

* Defective Catalytic Converter
* Engine misfires have damaged the Catalytic Converter
* Internal engine damage resulting in high oil consumption and/or a leaking Head gasket has damaged the Catalytic Converter

Common Misdiagnoses

* Oxygen Sensors are replaced when the real problem is a damaged Catalyst
* Catalyst is replaced when the real problem is internal engine damage, which is producing elevated emissions levels
* Catalyst is replaced when a misfiring engine is the real problem



Thanks for using FixYa - a 4 THUMBS rating is appreciated for answering your FREE question.

Jan 27, 2009 | 1999 Volkswagen Beetle

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