rowo87

One of my O2 sensors went bad but I didn't replace it and now my catalytic converter is messed up and throwing the efficiency code. If I just get a cat-back exhaust will the bad o2 sensor still throw a code or do I have to replace the sensor and get a new converter?

swittindoodle

the catalytic converter might not be bad, its probably throwing the code because the o2 sensor is bad. and getting catback wont solve the problem.
try getting a new o2 sensor and resetting the ecu. if the check engine light is still on then you may need a new cat.

It Wasn't Me

x2



Are there any codes in addition to P0420, rowo87?

gudoffer

how do u reset the ecu ?

It Wasn't Me

Disconnect the battery, or remove fuse number 6 (15amp) from your under-hood fuse box.



Edit: I forgot to mention that you need to put your car through Idle Relearn if you reset the ECU.


1. Make sure all electrical items are off.
2. Start the engine and hold it at 3,000 RPM without load (in Park or neutral) until the radiator fan comes on, or until the engine coolant temperature reaches 194° (90c)
3. Let the engine idle for about 5 minutes with the throttle fully closed.

If the radiator fan does come on, do not include its running time in the 5 minutes.

rowo87

Hey guys thanks for the quick replies. The only code it's throwing right now is the P0420 but after driving for awhile the cat seems to seize up and prevents the car from accelerating beyond about 25mph than if I pull over and let it cool down it drives fine until it gets too warm. Could this mean then converter is bad? Or will the O2 sensor alone prevent this from happening?

swittindoodle

neither. that doesnt sound like the cat or o2 sensor, all the cat does is burn off excess fumes from your exhaust, it shouldnt restrict your car from going more than 25 mph.and the o2 sensor does what it sounds like it reads the fumes and o2 levels before and after the cat. it sounds to me like you've got engine problems not exhaust.

SimpleAznMan

Your car went into limp mode, its confused over how much air/fuel to use due to your O2 sensor(s). Replace them so the ECU can correctly measure how much air/fuel to use. After replacing your O2 sensor(s), reset by either deleting the code with an OBD2 scanner OR hard reset by disconnecting the battery for 30 seconds. I recommend the OBD2 method so you don't have to redo your radio settings.

The code should have mentioned either Bank 1 or Bank 2. Bank 1 = Before Cat O2 sensor, Bank 2 = after Cat O2 sensor. The first one actually determines the air/fuel ratio to be used. Second one checks the gases AFTER cat converter to make sure your cat is working right.

If they are not fried, you can actually try to clean them off with a sensor safe cleaner first.


Ken

It Wasn't Me

Take it to Autozone, PepBoys, Advanced Auto, etc. etc. and have them check for stored codes.

We need to know all the codes that have been (or are being) thrown if we are going to provide remedial information.