Possible to clean Oxygen (02) Sensor on 2002 Camry LE 4cyl?

[GoldenTacoMan]

First of all, I had AutoZone read the code for me the other day when my check engine light came on, but made the mistake of not getting him to tell me what the actual code was, so if I need to go back and get it again, I can.

What he did say was that the problem was probably an 02 sensor with carbon build-up on it and that I could try cleaning it and if that didn't work I would have to replace it.

Before I go out and drop $80-$100 on a new sensor, I was wondering if anyone could explain how to clean it and/or how difficult it is.

Gratzi!

[JSM1284]

First off. Auto Zone people have NO CLUE about what causes a code. They just know how to read it. Most common 02 sensor failure is a circuit malfunction, Cleaning will not help, the actual circuitry is damaged.

[Hajoca]

The malfunction that JSM is referring to is the sensor itself, made of 'doped' ceramic which is not really cleanable after it's life is finished. Replace it.

Check that you have an O2 sensor and not an A/F (Air Fuel) sensor. the two types look similar, but are not interchangable, and give out a different signal to the ECU.

In regards to the O2 sensor, there is a vendor on Ebay that sells lightly used sensors dyno test ing. I have bought several and have used them for after cat sensor only.

[GoldenTacoMan]

Originally Posted by Hajoca

The malfunction that JSM is referring to is the sensor itself, made of 'doped' ceramic which is not really cleanable after it's life is finished. Replace it.

Check that you have an O2 sensor and not an A/F (Air Fuel) sensor. the two types look similar, but are not interchangable, and give out a different signal to the ECU.

In regards to the O2 sensor, there is a vendor on Ebay that sells lightly used sensors dyno test ing. I have bought several and have used them for after cat sensor only.

I found this, supposedly "new in box" on ebay. I'm cynic enough to wonder why it would be $16 new compared to the others that are over $100?

Also, is replacing this something a novice can do? I'm not ultra-mechanical, though I've changed my oil, replaced thermostat, etc.

[TRD VVTi]

Cleaning it won't help.

Replace the faulty sensor with an OEM sensor to avoid future headaches. The eBay sensor you listed is a piece of crap.

[kenny1773]

Confirm exactly what yours takes (I think the US built vs Japan built models might take different sensors) but I had VERY good luck on my old '95 camry just buying the generic Denso sensor with the correct # of
wires (either 1,2,3,4) and soldering the connector from the factory sensor on to the generic.

I think you car will take this one, but double check me, I am not positive.

http://www.densoproducts.com/more_info.asp?pid=2258


edited to clarify, don't buy a generic brand sensor from ebay, stick with Bosch or Denso.

You can't really clean these sensors, they just need to be replaced when they go bad.

[TRD VVTi]

It's best not to add splices into oxygen sensor wiring. You can change the restistance of the circuit which will give an inaccurate reading.

Unless you properly solder the connections with the right gauge and quality wiring you should just get an OEM properly fitting sensor. It will give you less headaches and less to worry about.

[GoldenTacoMan]

Just to follow-up, I went back to AutoZone today to get the reading again and the error code is PO420. Definition is Catalyst efficiency low-bank 1.

Is the consensus that this is likely an O2 sensor problem? Is there something I could test to narrow it down?

[JSM1284]

Have at it to confirm 02 sensor failure, Or Catalytic Converter:

P0420 - Catalyst System Efficiency Below Threshold (BANK1)

CIRCUIT DESCRIPTION


DTC Detection Condition
The ECM observes the waveform of the heated oxygen sensor located behind the catalyst to determine whether the catalyst performance has deteriorated.
If the catalyst functions normally, the waveform of the heated oxygen sensor located behind the catalyst switches back and forth between rich and lean much more slowly.
When the waveform of the heated oxygen sensor located behind the catalyst alternates flutteringly between rich and lean, it indicates the catalyst performance has deteriorated.


CONFIRMATION ENGINE RACING PATTERN

1. Connect the OBD II scan tool or hand-held tester to the DLC3.
2. Start the engine and warm it up with all the accessories switched OFF until the water temperature is stable.
3. Race the engine at 2,500-3,000 rpm for about 3 minutes .
4. When racing the engine at 3,000 rpm for 2 seconds and 2,000 rpm for 2 seconds alternately, check the waveform of the heated oxygen sensor.

Step 1 - 2
Step 3 - 4
INSPECTION PROCEDURE

HINT: Read freeze frame data using the hand-held tester or OBD II scan tool, as freeze frame data records the engine conditions when the malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.

[GoldenTacoMan]

What kind of reader would I have to buy to be able to do this test at home? I'm guessing the AutoZone lackeys won't sit there and go through this whole process w/ me.

[JSM1284]

One that Costs several thousands of dollars from Toyota. Or you can use a oscilloscope, or DVOM to measure values from the O2 sensors.

[GoldenTacoMan]

So I guess what you're actually saying is "go to a mechanic"? I mean, I think my self-described mechanical expertise above would preclude anyone from assuming I'm the type of guy who has an oscilloscope lying around.

Is replacing the O2 sensor as complicated as testing to see if there's anything wrong with it?

[JSM1284]

No, the sensor just Screws into the exhaust pipe.

[toyomoho]

The Toyota dealer uses a diagnostic tool that can display these waveforms to run down the trouble area per the procedure, AutoZone only has a code reader. To view the display you would need something like the reader below or an oscilloscope.

http://www.aeswave.com/products/Product.asp?i=546

The CAT should have a federal EPA mandated warranty of 8yr/80K miles; some states require an even longer warranty.

[JSM1284]

The problem is that with the code P0420, that says nothing about an 02 sensor. That code is saying that something is wrong with the cat. In that case, you need to check the Air/Fuel sensor before the cat, and the O2 sensor after the cat to verify those are functioning properly. If they are operating normal then there is a Catalytic Converter problem and it will need to be replaced.