check engine light

[buckeye_no12]

My check engine light came on after replacing all four o2 sensors and a catalitic converter...I read the code and it came back....catylistic efficency below thrushhold(bank1) does anyone have any idea what this means..and what i have to do to fix it???any information will help.....and also sorry i didnt search this much because i really didnt know what to search under...So can someone PLEASE help me???thanks for all replys....

[BlazerLT]

Reset your computer by pulling the negative terminal for overnight.

Then see if the code will come back.

If it comes back, you have a defective cat.

[MT-2500]

Originally Posted by buckeye_no12

My check engine light came on after replacing all four o2 sensors and a catalitic converter...I read the code and it came back....catylistic efficency below thrushhold(bank1) does anyone have any idea what this means..and what i have to do to fix it???any information will help.....and also sorry i didnt search this much because i really didnt know what to search under...So can someone PLEASE help me???thanks for all replys....

As BlazerLT said the code will need cleared and rechecked to see if it comes back.
But on some newer pcm/vcm you will need a scanner to clear code.
All new cats and 02 sensors may have been a over kill.
If the cats were bad you need to be checking for the reason they were bad or it could ruin the cat again.
Engine tune up and running up to par has a lot to do with it.
Post back the year and engine and mileage and the code no it had.
MT

[BlazerLT]

I would also reseat the #4 plug wire just to make sure it is on properly.

[buckeye_no12]

thanks for all the feedback i will check it out again today...i have already had the code cleared and it came back on.......this is a 1997 chevy blazer LT 4X4 4dr with a 4.3 automatic.....once again thanks for all replys....

[BlazerLT]

Cat is under warranty.

I suggest you go back to them and have them check it out.

[MT-2500]

Originally Posted by buckeye_no12

thanks for all the feedback i will check it out again today...i have already had the code cleared and it came back on.......this is a 1997 chevy blazer LT 4X4 4dr with a 4.3 automatic.....once again thanks for all replys....

You did not say what code no. or give us much info to help you.
And as BlazerLT said may be under check on that end.
But on a 420 or 430 code some info.
Good luck MT

http://www.troublecodes.net/articles/catfailure/


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 okay, 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 okay, go to next step. Ć 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 okay, 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 okay, 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 engineand raise engine speed to 2000 RPM. If manifold vacuum is now okay, 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 okay, 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 okay, 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.

[buckeye_no12]

ok sorry i didnt leave enough information last time but the code is P0420 and it is driving pretty well...nothing is reallying happening when I am driving it just came on and when i clear the code it stays off for a few days and then comes back on just when im driving...no certain time like going up hill or high rpm's just driving and it comes on.....I didnt buy the truck from the dealer so I dont have any warrenty.....I just hate that check engine light being on....it really gets on my nerves....well anymore feedback will be greatly helpful...
thanks again for everyones help...

[MT-2500]

Originally Posted by buckeye_no12

ok sorry i didnt leave enough information last time but the code is P0420 and it is driving pretty well...nothing is reallying happening when I am driving it just came on and when i clear the code it stays off for a few days and then comes back on just when im driving...no certain time like going up hill or high rpm's just driving and it comes on.....I didnt buy the truck from the dealer so I dont have any warrenty.....I just hate that check engine light being on....it really gets on my nerves....well anymore feedback will be greatly helpful...
thanks again for everyones help...

The warranty on cats or pcm/vcm is 8 year or 80K fed emmisions and should cover second owner and calf. emmisions may be more on it.
If it is still setting the code you need to get it checked out..
If there is a problem it may ruin the new cats or harm the engine.
Like I say tune up and engine running up to par is the first thing to test.
And then the things I posted in the other post.
Good Luck MT.