TLP_IS350

okay so i got the "Catalyst System Efficiency Below Threshold" code again. upstream and downstream O2 sensors are new and so is cat, wtf can it be? i have DC headers and downpip but stock cat back exhaust, could that be causing it?

ek-g6

Maybe be dc header is causing it. The header could be causing abnormal exhaust reading, if not are the wires frayed or ripped?

TLP_IS350

what wires are frayed or ripped?

ek-g6

the o2 sensor wires

TLP_IS350

they are new...?

ek-g6

I mean the other end of the o2 plugs. if you sucked in water, you have a good chance of the water going into one of the sensors, check the map sensor.

jdm_bones

iTrader: (5)

Also if you have a bad head gasket or coolent somehow got on the CAT, well then your CAT is bad, and it is not working right anymore. Coolent can also damage O2 sensors...just my 2 cents!

goferris

I know it's a stupid Q but did you reset the codes after you swapped the o2 sensors and such? Shouldn't be the header. I am running a dc 4-1 on my 01 GSR with no code. Ok.... I think I have a bad o2 sensor but the code isn't constantly on

jayare05

im goin threw the same *hit right now.. and have to take care of it fast cause here in wacky pa we need edmissions.. throwin a cel light, i tried runnin a simulator to the 2ndary o2 sensor but for some reason those things dont work in the integra. i put in a new secondary o2 sensor, then threw the p0420 code. just ordered a new cat hopin thats my real problem and well see where it goes from there. i have a 2.5 inch vibrant catback exhaust, and 4-1 header.. almost same situation my friend... gotta love obd2

TLP_IS350

yeah i did get the light reset and it didnt show up for about 30 miles. then its on again.

jayare05

so my new cat came in, we go to put it on, and we see that there is absolutely nothing wrong with my cat thats on my car now, so i put my old cat back on, and replaced the upstream 02 sensor. drove it about 95 miles and booked it to get emissions. It passed, and on the way home from the shop, the damn light came back. When me and my friend were taking my cat off, we noticed the springs in the bolts that go from the header to the cat were missing. Could this be possibly a reason im throwing this code? The only other thing i can think of is maybe because my header has a few dings in it from bottoming out? Im wondering why my car made it 95 miles with no light when i replaced the o2 sensor in the header, and every other time the light came back it came back under 35 miles..the helllll with obd2! any replies are welcomed.. and sorry for jackin ur thread man, but i were obvisally going threw the same problem.

JDM tuning702

im going through the same problem. my light pops back on between 30 and 60 miles of it being reset. i thought it was my crappy megan header so i went to acura and got all the stock gaskets for the header and put my stock one back on. whenever you go to autozone and get the printout for the code it says exhaust leak near o2 sensor, air/fuel concern or ignition concern...dunno if thatll help any of you guys to think of more things it could be, but im super stumped after trying to figure it out for the past couple months

jayare05

at this point im just tired of dealing with it, i got 2 new o2 sensors, so im just gonna do that non fouler trick to avoid throwing that stupid code.. or i hear the alluminum foil trick works just as well..

integrawow

Have you done the spark plug non-fouler trick to your rear o2 sensor yet?

TLP_IS350

well i replaced both o2 sensors and still light is on.

TLP_IS350

finally figured what was wrong. all i can say is Pulstar spark plugs suck! causes the computer to throw P0420 code. i replaced them with Desno Iridiums and the check engine light disappeared. Denso FTW

SpeedRacerEX-R

I'm throwing the same code. I think I'm just going to convert the ecm to obdI. obdII blows.

jayare05

I'm stillll having this problem.both sensors are new, and cat is good. I even tried the alluminum foil trick and I'm still throwin the code..I'm gonna attempt to change the plugs. Anyone else have any suggestions? Coolants fine and I have no exhaust leaks. Any troubleshooting help will be appriaciated.

Prelude Gundam

Usually P0420 means your integra needs someone to touch its *****, don't listen to those 'code readers'.

Also, if your fuel filter hasn't been replaced, it could cause the fuel mixture to be a little rich. Check your fuel pressure regulator if you're unsure about it being in proper working condition.

jayare05

ima give that a shot as well as puttin new plugs in it. this stupid code is blowing my mind. why the hell is this code so vague? you would think that they would assign a code to its own problem, not 1 code that could be multiple things.

jayare05

what ive done since the code has come on..

New..

4-1 header
header gasket
header dounut
new cat ( oem cat that my friend used for literally 15k )
both o2 sensors are new (sng brand)
changed the spark plugs w new ngk's
brand new 2.5 inch piping from the cat on.

and after all that.. my light is back on..

things ive heard to try that i havent yet.

new distributor cap and rotor?
try changing the coil, the fuel filter which looks like it was never changed period, it has newer ngk spark plug wires so im basically ruling that out. My hands are tied and i cant drive a car around without inspection stickers so at this point i dont no what to do. im going to take it to get the o2 sensors read but at this point im assuming there still good being there both not even a year old. im also ruling out the cat because its farely new, and on my old cat, ive tried the o2 simulator trick and it failed miserably. i just had the new cat welded on yesterday and the car sounded amazing and totally different leaving the shop and i was almost postive that was my problem until on the way home from work today, the light shined nice in bright in my face. ANYTHING would be greatly appriacated.

jayare05

Bump

jambo

o2 sensors tend not to be the problem . if you are confident the cat is in good condition ,then the problem is more likely to be a fuel mixture fault . p0171 is very common to come along with p0420 code ,this would indicate fuel mixture problem either too lean or rich . engine management is taking its readings from lots of sensors all that the o2 sensors are doing is reading the end product after the fuel is burnt. TRY REPLACING ENGINE TEMPRATURE SENSOR FIRST VERY CHEAP TO BUY ,APROX £18-£20 . THE FACT THE LIGHT COMES ON AFTER A SHORT DISTANCE COULD INDICATE THAT WHEN THERMOSTAT OPENS AT AROUND 80 degrees , THE COLD RADIATOR COOLANT MEETS THE HOT ENGINE COOLANT AND CAUSES A BAD SENSOR TO SAY I DONT LIKE THIS AND THUS GIVES THE ECU THE WRONG READINGS . THIS IS THE MOST LIKLEY CAUSE OF YOUR TROUBLES .just because temp gauge at dash is working ok does not mean the resistance readings being sent to ecu are ok. try and let us all know

BT216

wow i read all of this and same **** is happening to me, i replaced everything but the fuel filter and engine coolant temperature sensor ,hopefully thats the problem

jayare05

Hey man sorry for the late reply but I gave up on this damn code for awhile but its that time of the year and my inspections up at the end of the month. I'll replace the engine temp sensor and let you know how it goes. Any other suggestions? I'm at a dead stop w no ideas left after I change this temp sensor?