2002 Toyota Camry P0420 Check engine light

Discussion in 'Import Vehicles' started by just972, Apr 19, 2008.

  1. just972

    just972 Newbie

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    I have a 2002 toyota camry SE with 59162 miles, it has the 3. 0 V6 and auto tranny. The other day the check engine lot came on. I took it to the NAPA store and they read the code as P0420 Catalyst System Efficiency below threshold (bank 1). They said it could be 1 of 4 o2 sensors, or the catalyst. So I called the toyota dealer and the service dept manager stated it would be one of the front o2 sensors. I don't want to spend the $204 each on either of the front o2 sensors if it is the catalyst or either of the rear o2 sensors at $100 each, and vice versa I don't want to be screwed by the dealer and end up replacing the catalyst and two o2 sensors if the problem could be fixed by replacing one o2 sensor. Can anyone help me out on figuring out exactly which o2 sensor it is, or how do I know if the catalyst is bad? Also I have heard that you should replace a toyota sensor with a denso instead of a bosch? Is this correct? I have also found a toyota service bulletin 02404, which I think might pertain to this problem. Any help at this point will be greatly appreciated. Thankyou
     
  2. Jim Fairbanks

    Jim Fairbanks wrench

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    PO420 is bank1 sensor2..You can check the resistance on the sensor and if it is bad replace it,more than likely just a bad 02 sensor....here is a diagram of which one it is if you want to check it...Jim............HEATED OXYGEN SENSOR (Bank 1 Sensor 2)

    INSPECTION

    INSPECT HEATER RESISTANCE OF HEATED OXYGEN SENSOR (Bank 1 Sensor 2)



    Remove the driver's seat.
    Take out the floor carpet.
    Disconnect the oxygen sensor connector.

    Using an ohmmeter, measure the resistance between the terminals +B and HT If the resistance is not as specified, replace the sensor.
    Reconnect the oxygen sensor connector. Torque: 44 N.m (450 kgf.cm, 32 ft.lbf)
    Reinstall the floor carpet.
    Reinstall the driver's seat.


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  3. just972

    just972 Newbie

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    Thankyou for the quick response. Now, do you happen to know what the resistance between the terminals +B and HT should be?
     
  4. Jim Fairbanks

    Jim Fairbanks wrench

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    Sorry about that..thought I posted it with the second pic....Jim

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  5. kdauto

    kdauto wrench

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    Sorry to butt in here Jim but I strongly disagree. I'd say maybe 10% chance the O2 sensor is bad. 90% chance is that the Catalytic converter is bad.
    The whole point is moot, this should be covered under US emissions warranty 8yrs/80 000 miles. I would be contacting the dealership and asking if it's covered. Make sure there are no obvious exhaust leaks first. If an O2 heater was bad it would set a different code. The PCM is very precise in analyzing it's converters. If it says it's bad,90% of the time it is. Any other codes set?
     
  6. Jim Fairbanks

    Jim Fairbanks wrench

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    No problem Karl..You are right...I didn't think about the warranty on the cat...just972,you might want to ask the dealer about the cat...Jim
     
  7. kdauto

    kdauto wrench

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    Here's a link from one of our good techs,Rick. http://www.troublecodes.net/articles/catfailure/ It explains how the PCM tests the cat.
    Unless this is a salvage car, it should be covered 100%.
     
  8. just972

    just972 Newbie

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    Thankyou guys, It is not a salvage title. We bought the car with approx 30,000 miles and this is the first time the check engine light has ever come on. I do all of the rerular maintaince on it ie: oil change every 3k, air filter every 10 k, tranny fluid every 25k, tire rotate every other oil change. I am going to take it to the dealer for the 90 k service when it needs the timing belt. But I think I will bite the bullet and take it to the dealer for the check engine light this time. At the NAPA store they cleared the code for me and we have driven it approx 250 miles and it has not come back on. Will it need to be on when I take it to the dealer?
     
  9. kdauto

    kdauto wrench

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    I don't think they'll touch it for free with the code erased. That is a mistake. Never have incompetent people (people who just clear codes with a code reader=AKA parts salesman) touch the car. Lots of vital info is likely wiped from the PCM. There's freeze-frame data that helps immensely in diagnosis. Ask them but I'd drive till the light comes back on. A catalytic converter for this thing is likely 1200$. I wouldn't screw around maybe wasting your chance for a free replacement.
     
  10. csaxon

    csaxon Full Member

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    This discusses the 2002 Camry with p420.

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  11. kdauto

    kdauto wrench

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    OK info but a mistake on the tsb's which pertain only to the 4 cyl Camry.
     
  12. wap

    wap GO MOUNTAINEERS

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    Remember, the po420 code only indicates that the readings from the upstream o2 sensors are very close to the downstream o2 sensor. it is not idicative that the cat is bad. cat should be tested with a pyrometer. most cat convertors will last a lifetime. physical deformity is a clue to the cat being bad. if you check the inlet temp and the outlet temp, at idle, there may be as little as 30 degree diff. at 2000 rpm it may be a 200 to 300 degree diff. this only indicates that the cat is working, not bad. 500 to 600 degree diff will sometimes result in a cat meltdown. po420 is a code we usually find that indicates an engine problem. egr valve, pcv valve, secondary air pump, spark plugs, etc. have an exhaust shop replace the cat with a straight pipe, see if car runs better, i suspect it will not. good luck....check under the hood before changing the cat....wap
     
  13. kdauto

    kdauto wrench

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    Using a pyrometer on a modern 3 way cat (TWC) is inaccurate. Some models barely have any temp difference from inlet to outlet. OEMs warn that it's inaccurate testing. Also, relying on eyeballing pre and post cat waveforms is also guesswork. dIFFERENT PROGRAMS FOR DIFFERENT YEARS, EVEN DIFFERENT areas (Sorry, hit caps lock). The PCM ultimately decides if the algorithms it sees from the sensors fall into ok or bad status. Sometimes a P0420 is caused by other things, but in my experience, the P0420 and P0430 codes are usually the catalyst. Either way, this vehicle should be covered under warranty.
     

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