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Already replaced catalytic converter, oxygen sensor, tune-up. Nocs too high on heavy load test by 600 points. Performed tests suggested in manual on Air Intake system. Solenoids don't seem to have vaccum but don't know if shouold replace the two solenoids or it iselectricial. Volt test lowon solenoid. Rewtired honda man confined to wheelchair with MS unable to perform all tests in manual. Any suggestions. Not running hot nor is trans slipping so don't think it is EGR.
Getting your hands on an EGT sensor would help, along with hooking up an A/F gauge, A faulty coolant temp sensor could cause this issue without a doubt. Even using a infrared temp gauge would help, hitting each cylinder checking outside temp could indicate a lean or rich cylinder condtion.
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catalytic converter .
In order to control emissions, a catalytic converter converts any harmful exhaust emissions into harmless water vapor and carbon dioxide.
The powertrain control module (PCM) has the capability to monitor this process by using a rear-heated oxygen sensor (HO2S 2). The HO2S 2 , located in the exhaust stream past the catalytic converter, produces an output signal which indicates the storage capacity of the catalyst. This in turn indicates the catalysts ability to convert the exhaust emissions effectively. If the catalyst is functioning properly, the HO2S 2 signal will be far less active than the signal produced by the front oxygen sensor (O2S 1).
Hi there:DTC P0420 - Catalyst System Efficiency Below Threshold (Bank 1)
The catalytic converter has an oxygen sensor in front and behind it. When the vehicle is warm and running in closed loop mode, the upstream oxygen sensor waveform reading should fluctuate. The downstream O2 sensor reading should be fairly steady. Typically the P0420 code triggers the Check Engine Light if the readings of the two sensors are similar.
This is indicative of (among other things) a converter that is not working as efficiently as it should be (according to specs). It is part of the vehicle emissions system.
A code P0420 may mean that one or more of the following has happened:
Leaded fuel was used where unleaded was called for A damaged or failed oxygen sensor (HO2S) Downstream oxygen sensor (HO2S) wiring damaged or connected improperly The engine coolant temperature sensor is not working properly Damaged or leaking exhaust manifold / catalytic converter / muffler / exhaust pipe ******** spark timing The oxygen sensors in front and behind the converter are reporting too similar of readings Leaking fuel injector or high fuel pressure Cylinder misfire Oil contamination
Possible Solutions: some suggested steps for troubleshooting a P0420 error code include:
Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required. Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. The waveform of the sensor behind the converter should be more steady). Inspect the downstream heated oxygen sensor (HO2S), replace if necessary Replace the catalytic converter Overall probably the biggest mistake vehicles owners make when they have a P0420 code is to simply replace an oxygen sensor (H02S). It is important to do proper diagnosis so you're not wasting money replacing parts unnecessarily.
We strongly recommend that if you need to replace the catalytic converter that you replace it with an OEM unit. Second choice would be a high-quality replacement part. There are many stories in our forums where folks replaced the cat with a cheaper aftermarket one only to have the code return shortly thereafter.
One thing to note is that many vehicle manufacturers offer a longer warranty on emissions-related parts. So if you have a newer car but it's out of it's bumper-to-bumper warranty, there still may be warranty on this type of problem. Many manufacturers give a five year, unlimited mileage warranty on these items. It's worth checking into.
Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.
Generally, this code
is from a failed converter. Most exhaust or diagnostic shops can perform a converter back pressure test to confirm if the converter is failing.
DTC P0420 - Catalyst System Efficiency Below Threshold (Bank 1) The catalytic converter has an oxygen sensor in front and behind it. When the vehicle is warm and running in closed loop mode, the upstream oxygen sensor waveform reading should fluctuate. The downstream O2 sensor reading should be fairly steady. Typically the P0420 code triggers the Check Engine Light if the readings of the two sensors are similar.
This is indicative of (among other things) a converter that is not working as efficiently as it should be (according to specs). It is part of the vehicle emissions system.
Some suggested steps for troubleshooting a P0420 error code include:
Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required.
Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. The waveform of the sensor behind the converter should be more steady).
Inspect the downstream heated oxygen sensor (HO2S), replace if necessary
Replace the catalytic converter
Overall probably the biggest mistake vehicles owners make when they have a P0420 code is to simply replace an oxygen sensor (H02S). It is important to do proper diagnosis so you're not wasting money replacing parts unnecessarily.
We strongly recommend that if you need to replace the catalytic converter that you replace it with an OEM unit. Second choice would be a high-quality replacement part. There are many stories in our forums where folks replaced the cat with a cheaper aftermarket one only to have the code return shortly thereafter.
One thing to note is that many vehicle manufacturers offer a longer warranty on emissions-related parts. So if you have a newer car but it's out of it's bumper-to-bumper warranty, there still may be warranty on this type of problem. Many manufacturers give a five year, unlimited mileage warranty on these items. It's worth checking into.
Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.
Hi, P0420 code means a catalytic converter fault.
The catalytic converter has an oxygen sensor in front and behind it. When the vehicle is warm and running in closed loop mode, the upstream oxygen sensor waveform reading should fluctuate. The downstream O2 sensor reading should be fairly steady. Typically the P0420 code triggers the Check Engine Light if the readings of the two sensors are similar. This is indicative of (among other things) a converter that is not working as efficiently as it should be (according to specs). It is part of the vehicle emissions system.
Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required.
Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. The waveform of the sensor behind the converter should be more steady).
Inspect the downstream heated oxygen sensor (HO2), replace if necessary
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.
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.*&#$%
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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