Catalytic Convertor VS oxygen sensor?

Question

I have a 2000 toyota Celica with 85000 miles and the check engine light has been on for a long time. I KNOW that it has to to with emmitions and my mechanic said that my cat convetor might be shot. one way to check is to bang on it and listen for rattles.. well it desn't rattle and I have banged on it, so I THINK it's the oxygen sensors. there are two of them and I don't know what is the culprit. parts for that car can be very expensive and hard to find, so I would like to be sure. so what do you think? one both or all three? I also have a cold air intake and I was wondering if that might account for the air fuel ratio being off and setting that light on.

I know what the codes are and I would never trust a dealership, the problem is that the codes are not that specific in my repair manual, it only says... P0420 Catalyst system Efficiency below threshhold.. and what detects that? the oxygen senors? so what's really at fault?

Answer 1

The o2 sensor is that is being triggered is downstream of the cat. The o2 sensor measures temperature variances. The idea is that a cat will regulate the temperature of the exhaust gas pulses. If the sensor measures great temperature differences between the pulses it will trigger the p0420 code. Anyone who has installed a catless exhaust in cars with obd-II are familiar with this code. The o2 sensor only takes measurments at highway speeds so reset your ecu and see if highway driving sets it off. Many tuners "trick" the sensor by removing the sensor from the direct flow of the exhaust pulses so that less variation in temperature is detected, this technique employes 2 18mm spark plug anti foulers (search nasioc.com for part #'s and instructions).

Answer 2

ok nicely this would nicely be a complicated one for the reason which you may continuously replace one area and it seems to be the different. the main costly area to interchange is the cat converter, the terrific strategies to tell if the cat converter is undesirable without paying a tech to look at is is A. do you scent rotten eggs? sounds humorous yet that's the simplest sign, B. do you hear a noisy damn noise coming from below your automobile? if not then it would desire to be purely the o2 sensor. Now if it have been me i could replace the o2 sensor that's the closest to the cat converter, because of the fact this may well be why it pulled codes for the two. would desire to you have o2 sensors till now and after your converter replace the only in front. If that sensor is undesirable, the computing gadget will possibly not have the skill to make certain if the malfunction is coming from the cat converter or the 02 sensor. So in end pass with the 02 sensor and pass your arms. stable success i desire this helped!`

Answer 3

I don't know why you don't trust us but P0420 is most likely a cat and they can still burn out and not rattle , if O2 was a problem it would have a O2 code with the P0420 you said its been on for a long time , two bad you don't like your dealer because cats are in warranty for 8years 80,000.

Answer 4

Pay the money and have the toyota shop scan the code. Then you will know exactly what needs to be done. Can be very expensive to 'throw parts at the car'. Quit wasting time and money and do it right the first time.