CEL code P0420
autorem123
01-25-2007, 12:33 PM
Check Engine Light is on, had it scanned at parts store and result:
Catalyst Efficiency Below Threshold (Bank 1)
Can this light be shut off if I buy a scanner and delete or can the converter be affected by fuel additives? Or do I need to replace the whole darn $$ converter? Thanks Mike in cold NH .
Catalyst Efficiency Below Threshold (Bank 1)
Can this light be shut off if I buy a scanner and delete or can the converter be affected by fuel additives? Or do I need to replace the whole darn $$ converter? Thanks Mike in cold NH .
Jay!
01-25-2007, 06:09 PM
What's your year/mileage?
Federal Emissions Warranty mandates that Subaru covers your catalytic converter to 8 years / 80,000 miles.
Federal Emissions Warranty mandates that Subaru covers your catalytic converter to 8 years / 80,000 miles.
MT-2500
01-25-2007, 06:57 PM
Check Engine Light is on, had it scanned at parts store and result:
Catalyst Efficiency Below Threshold (Bank 1)
Can this light be shut off if I buy a scanner and delete or can the converter be affected by fuel additives? Or do I need to replace the whole darn $$ converter? Thanks Mike in cold NH .
One major problem with a cat code is engine running or engine miss.
How is the tune up and engine running?
The code may be caused by several things and does not man a bad cat.
The code can be cleared with a scanner but if the problem is still there it will come right back on.
Here is the testing procedure for cat codes.
http://www.troublecodes.net/articles/catfailure/
Or a little info on it. Let us how how it goes.
DTC P0420, P0421, P0430 & P0431: Check Possible Cause Of Misfire DTC P0420 and P0421 indicates bank one catalyst system efficiency is minimum requirement. DTC P0430 and P0430 indicates bank 2 catalyst system efficiency is minimum requirement. Possible causes are as follows: Use of leaded fuel. Oil contamination. Cylinder misfire. Fuel pressure too high. HO2S sensor improperly connected. Damaged exhaust system component. Faulty ECT sensor. Faulty HO2S. Ensure ignition timing is correct. Retrieve all Continuous Memory DTCs. If misfire code(s) is not present, go to next step. If misfire code(s) is present, isolate cylinder and repair as necessary. Check HO2S Monitor DTCs If DTCs P0136, P0138, P0140, P0141, P0156, P0158, P0160, or P0161 were present in step 1), service as necessary before continuing. If none of these codes are present in step 1), go to next step. Check ECT Sensor DTCs If DTCs P0117, P0118, P0125 or P1117 were present in step 1), service as necessary before continuing. If none of these codes are present in step 1), go to next step. If any codes except P0420, P0421, P0430 and/or P0430 were present in step 1), service as necessary before continuing. If no codes except P0420 and/or P0430 were present in step 1), go to next step. Check Rear HO2S Wiring Harness Turn ignition off. Ensure HO2S wiring harness is correctly routed and connectors are tight. Repair or replace as necessary. If wiring harness and connectors are ok, go to next step. Check Fuel Pressure Turn ignition off. Release fuel pressure. Install fuel pressure gauge. Start engine and allow to idle. Note fuel pressure gauge reading. Increase engine speed to 2500 RPM and maintain for one minute. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to CIRCUIT TEST HC . Check For Exhaust System Leaks If exhaust system leaks, it may cause catalyst monitor efficiency test to fail. Inspect exhaust system for cracks, loose connections or punctures. Repair or replace as necessary. If exhaust system is okay, go to next step. Check For Exhaust System Restrictions Inspect exhaust system for collapsed areas, dents or excessive bending. Repair or replace as necessary. If exhaust system is ok, go to next step. Check Manifold Vacuum Install tachometer. Connect vacuum gauge to intake manifold vacuum source. Start engine and raise engine speed to 2000 RPM. Manifold vacuum should rise to more than 16 in. Hg. If manifold vacuum is ok, go to next step. If manifold vacuum is low, go to step 11). Leave tachometer and vacuum gauge connected. Start engine and raise engine speed to 2000 RPM. On a non- restricted system, manifold vacuum should quickly rise to normal range as increased RPM is maintained. On a restricted system, manifold vacuum will slowly rise to normal range as increased RPM is maintained. If manifold vacuum is ok, no indication of exhaust leak or restriction has been detected and testing is complete. If manifold vacuum is low or slow to respond, go to next step. Leave tachometer and vacuum gauge connected. Remove exhaust pipe from exhaust manifold. Start engine and raise engine speed to 2000 RPM. If manifold vacuum is now ok, fault is downstream from exhaust manifold. Reconnect exhaust pipe to exhaust manifold and go to next step. If manifold vacuum is still low or slow to respond, fault is in exhaust manifold or intake manifold gasket. Repair or replace as necessary and repeat QUICK TEST. Leave tachometer and vacuum gauge connected. Disconnect muffler/tailpipe assembly from rear of catalytic converter. Start engine and raise engine speed to 2000 RPM. If manifold vacuum is now ok, fault is in muffler/tailpipe assembly. Repair or replace as necessary and test drive vehicle to verify elimination of symptom. If manifold vacuum is still not ok, fault is in catalytic converter. Repair or replace as necessary. Check tailpipe/muffler assembly for debris from catalytic converter. Test drive vehicle to verify elimination of symptom.
Catalyst Efficiency Below Threshold (Bank 1)
Can this light be shut off if I buy a scanner and delete or can the converter be affected by fuel additives? Or do I need to replace the whole darn $$ converter? Thanks Mike in cold NH .
One major problem with a cat code is engine running or engine miss.
How is the tune up and engine running?
The code may be caused by several things and does not man a bad cat.
The code can be cleared with a scanner but if the problem is still there it will come right back on.
Here is the testing procedure for cat codes.
http://www.troublecodes.net/articles/catfailure/
Or a little info on it. Let us how how it goes.
DTC P0420, P0421, P0430 & P0431: Check Possible Cause Of Misfire DTC P0420 and P0421 indicates bank one catalyst system efficiency is minimum requirement. DTC P0430 and P0430 indicates bank 2 catalyst system efficiency is minimum requirement. Possible causes are as follows: Use of leaded fuel. Oil contamination. Cylinder misfire. Fuel pressure too high. HO2S sensor improperly connected. Damaged exhaust system component. Faulty ECT sensor. Faulty HO2S. Ensure ignition timing is correct. Retrieve all Continuous Memory DTCs. If misfire code(s) is not present, go to next step. If misfire code(s) is present, isolate cylinder and repair as necessary. Check HO2S Monitor DTCs If DTCs P0136, P0138, P0140, P0141, P0156, P0158, P0160, or P0161 were present in step 1), service as necessary before continuing. If none of these codes are present in step 1), go to next step. Check ECT Sensor DTCs If DTCs P0117, P0118, P0125 or P1117 were present in step 1), service as necessary before continuing. If none of these codes are present in step 1), go to next step. If any codes except P0420, P0421, P0430 and/or P0430 were present in step 1), service as necessary before continuing. If no codes except P0420 and/or P0430 were present in step 1), go to next step. Check Rear HO2S Wiring Harness Turn ignition off. Ensure HO2S wiring harness is correctly routed and connectors are tight. Repair or replace as necessary. If wiring harness and connectors are ok, go to next step. Check Fuel Pressure Turn ignition off. Release fuel pressure. Install fuel pressure gauge. Start engine and allow to idle. Note fuel pressure gauge reading. Increase engine speed to 2500 RPM and maintain for one minute. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to CIRCUIT TEST HC . Check For Exhaust System Leaks If exhaust system leaks, it may cause catalyst monitor efficiency test to fail. Inspect exhaust system for cracks, loose connections or punctures. Repair or replace as necessary. If exhaust system is okay, go to next step. Check For Exhaust System Restrictions Inspect exhaust system for collapsed areas, dents or excessive bending. Repair or replace as necessary. If exhaust system is ok, go to next step. Check Manifold Vacuum Install tachometer. Connect vacuum gauge to intake manifold vacuum source. Start engine and raise engine speed to 2000 RPM. Manifold vacuum should rise to more than 16 in. Hg. If manifold vacuum is ok, go to next step. If manifold vacuum is low, go to step 11). Leave tachometer and vacuum gauge connected. Start engine and raise engine speed to 2000 RPM. On a non- restricted system, manifold vacuum should quickly rise to normal range as increased RPM is maintained. On a restricted system, manifold vacuum will slowly rise to normal range as increased RPM is maintained. If manifold vacuum is ok, no indication of exhaust leak or restriction has been detected and testing is complete. If manifold vacuum is low or slow to respond, go to next step. Leave tachometer and vacuum gauge connected. Remove exhaust pipe from exhaust manifold. Start engine and raise engine speed to 2000 RPM. If manifold vacuum is now ok, fault is downstream from exhaust manifold. Reconnect exhaust pipe to exhaust manifold and go to next step. If manifold vacuum is still low or slow to respond, fault is in exhaust manifold or intake manifold gasket. Repair or replace as necessary and repeat QUICK TEST. Leave tachometer and vacuum gauge connected. Disconnect muffler/tailpipe assembly from rear of catalytic converter. Start engine and raise engine speed to 2000 RPM. If manifold vacuum is now ok, fault is in muffler/tailpipe assembly. Repair or replace as necessary and test drive vehicle to verify elimination of symptom. If manifold vacuum is still not ok, fault is in catalytic converter. Repair or replace as necessary. Check tailpipe/muffler assembly for debris from catalytic converter. Test drive vehicle to verify elimination of symptom.
4Wheel
01-26-2007, 08:13 PM
MT would you mind expanding a bit on the subject?
:cheers:
Great post!
:cheers:
Great post!
flamaest
12-23-2007, 05:44 PM
There is a lot of mention of Fuel Pressure in the catalytic converter diagnosis.
If I just changed the Fuel Filter on my 2000 Subaru Legacy GT [135k] and I JUST got a P0420 RIGHT AFTER, what is the chance my fuel filter is doing something weird/bad with my Fuel Pressure?
Also, I am running Platinum plugs installed about 30k ago, I heard this could cause a P0420.
Thanks,
Fabian
If I just changed the Fuel Filter on my 2000 Subaru Legacy GT [135k] and I JUST got a P0420 RIGHT AFTER, what is the chance my fuel filter is doing something weird/bad with my Fuel Pressure?
Also, I am running Platinum plugs installed about 30k ago, I heard this could cause a P0420.
Thanks,
Fabian
MT-2500
12-23-2007, 06:12 PM
Welcome to AF.
This post is almost a year old.
Always check date on a post and if it is old let it sleep.
Go to your correct forum for a Subaru and start a new thread and someone will help you.
Read In Post 3 it covers checking fuel pressure checking as a cause for a cat code.
Also engine miss as a cause for cat code.
Good luck
MT
This post is almost a year old.
Always check date on a post and if it is old let it sleep.
Go to your correct forum for a Subaru and start a new thread and someone will help you.
Read In Post 3 it covers checking fuel pressure checking as a cause for a cat code.
Also engine miss as a cause for cat code.
Good luck
MT
flamaest
02-14-2008, 12:03 PM
FYI: My problem did turn out to be due to the fuel filter change.
After the filter change,
The combination of a temporary fuel pressure drop and some engine-knocking due to a temporary air-gap in the fuel line caused the CAT-Converter P0420 flag to be raised.
I spoke to my local mechanic and he also said this is definitely possible, so we cleared the P0420 code and it never came back, it been 5k miles.
Peace,
Fabian.
After the filter change,
The combination of a temporary fuel pressure drop and some engine-knocking due to a temporary air-gap in the fuel line caused the CAT-Converter P0420 flag to be raised.
I spoke to my local mechanic and he also said this is definitely possible, so we cleared the P0420 code and it never came back, it been 5k miles.
Peace,
Fabian.
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