Check Engine - Oxygen Sensor

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Check Engine - Oxygen Sensor

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Check Engine - Oxygen Sensor - 4/14/2008 8:11:31 AM

jcamry

Posts: 2
Joined: 4/14/2008
Status: offline

Hi, I have a 2000 camry 4 cyl. with 153,000 mi. I had a hole in my exhaust pipe and needed to replace the front flex pipe assembly. I had it done at Meineke with after market part. I know, Toyota wanted $1,300 for the part excluding labor and Meineke did for about $400.00 total. About 1 week after replacing, the check engine light came on with code P0420. I cleared the code 2 times and it came back.
I brought back to Meineke (also had it read by 2 other service places) and was told I had to replace the O2 sensor before Cat. (air fuel sensor on Cal. emissions). I replaced myself and cleared the code. I drove about 8 miles with no problem. The next morning on way to work, I got about 10 minutes from home and the check engine light came back, same behavior as before replacing sensor. Could this be the rear sensor needs to be replaced?
Thank you for any help.

< Message edited by jcamry -- 4/14/2008 8:14:47 AM >

Post #: 1

RE: Check Engine - Oxygen Sensor - 4/14/2008 2:21:10 PM

toyomoho

Posts: 729
Joined: 1/24/2008
Status: offline

The computer compares the output of the oxygen sensor located before the CAT with one after to determine if CAT efficiency has deteriorated.

If the CAT is OK, the output of the sensor after the converter switches slower then than the waveform of the sensor before the CAT. If both sensor outputs vary at similar rate CAT performance may have deteriorated or there is a problem with the sensors. Code P0420 is then generated.

The computer has no direct way of testing the CAT; as such the problem could also be the sensors. A shop can do further testing to narrow down the problem.

Problem areas include exhaust system leaks, sensor(s) or CAT.

Keep in the mind the computer has trouble codes for both front and rear sensor troubles. As such if a sensor were the problem another code might pop up another code and the P0420 code.

(in reply to jcamry)

Post #: 2

RE: Check Engine - Oxygen Sensor - 4/15/2008 7:06:44 AM

jcamry

Posts: 2
Joined: 4/14/2008
Status: offline

Thank you for the explanation.
I am going to change the rear sensor also then see if there is any change, since the mileage is up there. If not, I think you are correct in getting a pro to troubleshoot.
Thanks again.

(in reply to toyomoho)

Post #: 3