Accent o2 sensor code failed, replaced, but not fixed. Car Trouble
 

I have 2003 Accent 1.6L engine. At about 48,000 miles I got a check engine light on so I had it scanned and it turned out that my o2 sensor behind the catalytic converter had gone bad. I changed that o2 sensor and the problem was solved. Now I am at about 59,000 miles and I got another check engine light that has come up. I had my obd2 scanned and the code came up reading "slow response from the o2 sensor before the catalytic converter", so I had that one replaced. After about 150 miles on that sensor the check engine light came back on with the same code. I returned the part (which was strangely covered with a great amount of carbon for only being in my car 9 days), and got a completely new one. I installed it and also replaced my plugs too. After about 150 miles the check engine light is back with the same code as before, "slow response from the o2 sensor before the catalytic converter". Does anyone know what could be wrong with my car? I can't figure it out. Something is causing the o2 sensor before the catalytic converter to fault, but I don't know what it is. Any help would be greatly appreciated. Thanks.

RE: Accent o2 sensor code failed, replaced, but not fixed. Car Trouble
 

Hi there i have a 97 accent with the same problem as yours and have done everythingto the car.The other dayi removed the 5/16 vaccum hose from the back side of the intake manifold plenum that goes to the EVAP canistor. I capped the plenum side and pluged the hose side and took the car for a ride and what a difference it made so i know that i have a problem with the EVAP system . Good Luck

RE: Accent o2 sensor code failed, replaced, but not fixed. Car Trouble
 

I am just wondering what code are reading is P0133 Oxygen Sensor Circuit Slow Response (Bank1, Sensor1)... Because a friend of mine encountered the same problem as yours... Anyway, if in case it is theP0133 this involves the front oxygen sensor on the driver's side before your Hyundai catalytic converter. This code indicates the engine air fuel ratio is not being adjusted by the oxygen sensor signal or the ECM as expected to do so, or not adjusted as often as expected to do so once the engine is warmed or under normal engine use. You will likely not notice any drivability problems, although there may be symptoms. This code could have caused by faulty oxygen sensor, wiring to the sensor is broken / frayed or there is an exhaust leak... The simplest thing to do is to reset the code and see if it comes back. If the code comes back, the problem is more than likely the front driver's side oxygen sensor. You will likely wind up replacing it but you should also consider these possible solutions of checking and fixing any exhaust leaks, look for wiring problems (shorted, frayed wires), check also the frequency and amplitude of the oxygen sensor (advanced), verify if your O2 sensor is deteriorating / contaminated, replace if necessary or look for inlet air leaks and lastly check the MAF sensor for proper operation.. Good luck!!!