rlx101

UPDATE:

2002 ES300, 154,000 miles (all highway)
I got this CEL - PO430 - Catalyst efficiency below treshhold ( Bank 2 ).
(i've been getting 25-27 mpgs, calculated at the pump, not sure if this is important)

I ordered OBD II --> USB reader off ebay for 25$ shipped and installed this software: OBD 2007



I am trying to figure out why i Have PO430 and why it appears/disappears for a few weeks. If this was a cat converter wouldnt i have CEL permanently?

I took some screen shots, this is my first time running such extensive OBD diagnostics. Please take a look and comment if you have an idea about what might be going on here.
(i must say the software is pretty cool and very user friendly, tons of cool features to play with)





610 rpm:



2200rpm:



freeze frame data when code first came up? :



not sure what this is:



O2 sensors while revving up 600->1400rpm:



O2 sensors 1400-->600rpm:



2krpm sensors:



trims at 600rpm:



fuel analysis at 600 rpm:



fuel analysis at 2000 rpm:

rlx101

guys is this correct passanger side after cat oxygen sensor? http://www.rockauto.com/catalog/rafr...7&a=FR23-15487

Does anyone have a diagram with sensor names/positions for 2002 ES#300?
Do i need bank 2 sensor 2?

bank1 - driver side
bank 2 pasanger side
sensor1 - before cat
sensor2 - after cat

is this correct? thanks.

GEORGE_JET

I would recomend reading the post (located several posts below), about the 99 with code p0420. I attached a file to this post that describes the code, and how to troubleshoot. p0420 is the same problem, but bank 1, your code is for bank 2. The attachement describes the steps you need to take to troubleshoot this.

rlx101

hi George, thanks for the info. So the OBDII scan tool can read the waveform of any O2 sensor, correct? What kind of waveform will you get if the sensor is faulty? How can i tell if my pre-cat bank 2 O2 sensor is ok?

now i see why you check pre-cat sensor first and then after cat. found this explanation:

what i dont understand is if pre-cat a/f sensor is bad then why is it not throwing a code???

steviej

iTrader: (1)

not quite correct. Since the ES engine is mounted transversely, there is no drivers or passenger side reference.

Bank 1 is the three cylinders closest to the windshield
Bank 2 is the three cylinders closest to the radiator.

your are correct in you sensor positions.

check your PM.

steviej

GEORGE_JET

Not all scanners will show you the waveform, some (like my mt2500, will tell you the voltage, and crosscounts). From my understanding of the article, the ECM determines that a cat is bad if there are significant changes in the post cat O2 sensors since during normal operation the engine is switching between rich/lean multiple times per minute (this number is called the crosscounts).
The cat will use the extra O2 to oxidze the exhaust gases. Hence you should not see significant changes in O2 downstream of the cat.

As far as checking the function of the pre-cat O2 sensor, if it is switching properly, then you will know for sure that it is good. Of course there are several things that will prevent it from switching, that are not related to sensor failure.

Gerson

iTrader: (1)

Pretty much a P0420 code would likely be the cats. If the sensors does not remedy your issue, the whole assembly should be replaced along with the sensors and reset the fuel trim by reprogramming the ecm. I work for Toyota and I see issues like this every once in awhile.

GEORGE_JET

Anyway, as for as the ECM determining if the Pre-cat O2 sensor is bad. The ECM can determine if the heater circuit is functioning, but if the O2 signal is low / or high, the ECM will just assume that the fuel curve needs to be adjusted, and it will change the short term, and long term fuel curves to add or subtract fuel.

Anyways, that type of stuff needs to be checked with a scanner, do you have one availible? If not there are several USB versions availible, (check ebay auctions), they run in the $40 ~ 50 dollar range. I do not know if they are capable of bi-directional communication. Bi directional comm can come in very handy at times. IE like when you want to bleed the ABS unit, you need to be able to give the ABS computer a command to open all valves. Several other times like that.

Hope this helps a little.

rlx101

geroge, stevie and gerson thank you for all the help ! lots of info here need to be digested. i have an access to the scanner not sure which model i may just get the one that reads all this stuff.

Gerson, are you saying that i may end up replacing sensor twice? Cant converter be replaced separately from sensors? i've found universal magnaflow catalytic converters in the $100-$300 range.

GEORGE_JET

The sensors should not have to be replaced twice. Generally you want to verify that the pre-cat O2 sensor is working, switching, and check the trim If everything looks fine up to that point. Check the post cat sensor, it it is switching, that indicates that the cat is not working. Also check the temp of the cat, it should be around 100 deg hotter than the upstream pipe. Of course use caution around the cat unless you want to get roasted.

Gerson

iTrader: (1)

Im sorry, I meant the cats if it still throwing CEL codes after the sensor replacement. U could go with universal cats if u want but have a good shop weld it up for u and get the proper sized cats for it. Buyin the oem assembly is pretty expensive but it comes with warranty from the dealership (I think 6 years or so).

mmatheny

You can get a cat online for less than $100.

rlx101

UPDATE:

George thank you for mentioning that OBD II to USB scanner from feeBay. I did some reading and will be ordering one from Hong Kong. Its not expensive and there are people who tested it with different applications. Go through this thread on saturn forums for more detailed information: http://www.saturnfans.com/forums/sho...d.php?t=135505

I did not know that OBD does so many cool things!!! (on board diagnostics, duuhhh!) My plan is to test performance of all 4 oxygen sensors and the catalytic converter.

On a side note - my check engine light disappeared... The car was parked over the weekend and also the temperatures here dropped down to ~55F (from ~65F). I am not sure if outside temperature has anything to do with this... I've been driving it for 3 days without CEL now.

mmatheny, are those cats for 100$ good quality? What brand is that?

GEORGE_JET

OBDII is a universal standard mandated by the government. The laws dictate the location (within a certain distance of the steering colum). type of connector, and a base set of codes. Manufactors can add their own codes as they feel fit, but the base codes must be numbered according to federal laws. Which means that a OBDII scanner will plug into any auto, or light truck sold in the US.

mmatheny

I'm sure they are after market. You can test a bad cat with a laser temp probe - if the cat is lighting up (term for increasing in heat) the temp will be higher at the pipe coming out than at the pipe coming in. That's how a cat works.