[joea]

Recently got a 2000 camry 4 cylinder auto Cal emissions 170,000, knowing it would need timing belt soon. Had new tires, struts, rear cat. Ran fine for some weeks. I did replace thermostat (oem) (running a bit cold), air filter (old one has mangled seal, a bit dirty) and heater fan resistor.

After a couple weeks got P0420. Reset, stayed off. Came a cold snap (like 0 for a few days) and noticed an oil leak. Got real bad after a few days. Coming from timing cover around crank. Got so bad I parked if for a rental to get to work. Still way to cold for me to work outside. Decided I would be better of paying to fix it than rent and still have to fix it. Found a local good rep shop that would to the labor with my parts.

Replaced timing belt (ASIN kit with wp, etc) belts, seals and oil pump rotor set. Nice job they did too. CEL was off.

Now the CEL comes on every trip to or from work (60 mile run on highway). Took freeze frames, links below. Perhaps some one with experience can offer an interpretation. For me it must be the front cat.?

(Edited to remove PIC that did not render well and add text below) I'm a bit puzzled why the long term fuel trim changed so radically on the last one.

Day1

FUELSYS1 CL
LOAD_PCT 63.9
ETC 178
SHRTFT1 0.0
LONGFT1 3.1
MAP 19.2
RPM 1845
VSS 39
IAT 23


Day2

FUELSYS1 CL
LOAD_PCT 52.2
ETC 196
SHRTFT1 1.6
LONGFT1 3.1
MAP 15.1
RPM 2793
VSS 76
IAT 50

Day3

FUELSYS1 CL
LOAD_PCT 67.9
ETC 192
SHRTFT1 -1.6
LONGFT1 9.5
MAP 19.8
RPM 2628
VSS 71
IAT 55

 

[dc_98_cam]

There seems to be some inconsistency in the LTFT number, but not too serious ... greater than 10%.
... Suggest that you add a bottle of Seafoam injector cleaner to a full tank of gas, and monitor the trim numbers to see if there are any changes. 170k miles ... just keep watching it for a while.

 

[mcgowaw]

got rid of my 420 cat code using 2 bottles of cataclean from autozone according to directions.
tony

 

[insightbrewery]

Car has good power? I'd check the front cat to make sure the honeycomb hasn't fallen off and clogged it. I got a 420 on a 2000 ES300, the owner put a sensor spacer in and the code went away...car still had no power, turned out the front bank element came loose and blocked the pipe.

 

[joea]

got rid of my 420 cat code using 2 bottles of cataclean from autozone according to directions.
tony

I used CRC guaranteed to pass. That seems to have helped. The frequency of the code is now about 150 miles per occurence. The Fuel trim has gone down to around 2.4 % which I take to mean I had a dirty intake/fuel system.

I may run a couple cans of cataclean through it to see if it clear completely. However, how to diagnose this further? How can I isolate this to front or rear cat if necessary? Calif, Emissions. I believe the front fuel/air sensor is orginial (170,000) as it says Toyota on it. Maybe I should swap that out just for grins?
(expensive tho)

 

[cj1]

How can I isolate this to front or rear cat if necessary?
When rear cat was replaced was there an O2 sensor to the rear of it?

 

[joea]

How can I isolate this to front or rear cat if necessary?
When rear cat was replaced was there an O2 sensor to the rear of it?

Former owner said an O2 sensor was replaced. I assume it's the one behind the cat as the one in the front looks original. It did get pretty wet from the oil leak, but I doubt that hurt it any.

I do have that aftermarket techstream deal, so I may dig into it with that. Only used it once so don't remember all it can tell me.

 

[joea]

To refresh this thread -

I continue to have this issue. LT fuel trim varies a lot. I understand that is not normal. ST fuel trim does also, apparently as it should. Hooked up a techstream clone. I fumbled around a bit and found where I could do a sensor check. Bank 1 Sensor 1 (Fuel air in this case) showed no data found. Bank 1 Sensor 2 did show data. A sine wave whose peaks did seem to vary some as I goosed the gas. I was a bit puzzled by this as I thought the rear sensor would be more steady state.

Fumbled around a bit more and found where I could graph, more or less, real time. I was puzzled to see both semsors at a steady state, up near max on the line graph. I was under the impression that the front sensor would vary a lot and the rear might, but should not mimic it.

My first thought is to suspect the front AF sensor, but, I have not thought this out, nor am I familiar enough with techstream to know how to read it properly.

My swing has stopped and my legs are tired. Push?

 

[mcgowaw]

a/f sensors hang around 3.3v. they don't show a sine wave from .1 to .9mv like an o2 does.
both should respond to a wot throttle blip rich/lean condition if they're working.

neither should peg at the top of their respective graphs as this means the a/f is pegged rich and the o2 is pegged lean, assuming you've got the tool setup correctly.

the rear (assuming b1s1 is a/f and b1/s2 is an 'after the cat' o2) should vary slightly up and down but not very fast (< ~1hz) and should stay mainly below the mid/450mv line denoting a good cat.

in your case, as i said earlier, run some cataclean per the instructions and that might clean the cat.
if not, then time to replace.

tony

 

[joea]

a/f sensors hang around 3.3v. they don't show a sine wave from .1 to .9mv like an o2 does.
both should respond to a wot throttle blip rich/lean condition if they're working.

neither should peg at the top of their respective graphs as this means the a/f is pegged rich and the o2 is pegged lean, assuming you've got the tool setup correctly.

the rear (assuming b1s1 is a/f and b1/s2 is an 'after the cat' o2) should vary slightly up and down but not very fast (< ~1hz) and should stay mainly below the mid/450mv line denoting a good cat.

in your case, as i said earlier, run some cataclean per the instructions and that might clean the cat.
if not, then time to replace.

tony

I did run cataclean thru it, made no difference. Both line graphs are near the top of their range and did not vary. I did not do WOT at idle. I may take it on the road later to try that with an observer or driver.

 

[joea]

To refresh. The previous owner said the cat and sensor had been replaced. It does look like newer stuff in back, but I'm certain the front stuff is original.

 

[betaerror]

I had two cars whose light was related to the CAT, not my own cars, jus wor ked on them. One had the wrong plugs and the other had worn plugs and wires. After change reset light and waited for all emissions sensor readyness. No p0420 has been over a year.

 

[PeTe520]

If you spilled oil on the o2 sensor this will make the sensor read weird readings, try spraying brake clean on the holes of the o2 sensor to try to get the oil out of there.. when I first started out at Toyota in 2005 I started in the lube line and every time anyone of the lube guys would spill oil on the o2 sensor we would have the clean eng light on and we had to replace the sensor..

If you can I would go to the junk yard and pull some o2 sensors off a Toyota 1996-2001 are the same I believe and swap them on your car and see what happens ...

If you have or if you don't get an inferred thermometer you can get one at your local auto parts store, check the temps between the two cats at operating temp if one is hotter by a lot you know you have to replace the hot one because it will be restricted and glowing red at night..

One time I did my T-belt on my 99 Camry and was replacing the valve covers and for some reason I looked into an air intake hole on the upper premium and noticed a fuel injector dripping gas like one drop a second.. before I R&Red my T-belt I would misfire while I was idle if at a light or if I was just idling for a long time not a real big deal once in awhile it would stall but would start right away and never throw a code.. after t replaced the injector I never had that idle proble again...I just found out a year or so ago that there is a TSB for such issue your having check pics ... jus some food for thought

 

[joea]

I had two cars whose light was related to the CAT, not my own cars, jus wor ked on them. One had the wrong plugs and the other had worn plugs and wires. After change reset light and waited for all emissions sensor readyness. No p0420 has been over a year.

The car had pretty new looking double platinum bosch plugs in it. Not the dual electrode kind. I put in the Denso OEM (new). Throttle response is better as cruise control holds speed better. But after 120 miles the light came on again.

 

[joea]

a/f sensors hang around 3.3v. they don't show a sine wave from .1 to .9mv like an o2 does.
both should respond to a wot throttle blip rich/lean condition if they're working.

neither should peg at the top of their respective graphs as this means the a/f is pegged rich and the o2 is pegged lean, assuming you've got the tool setup correctly.

the rear (assuming b1s1 is a/f and b1/s2 is an 'after the cat' o2) should vary slightly up and down but not very fast (< ~1hz) and should stay mainly below the mid/450mv line denoting a good cat.

in your case, as i said earlier, run some cataclean per the instructions and that might clean the cat.
if not, then time to replace.

tony

I would think the front one should vary quite a bit, as that is what feeds the fuel trim, if I am not mistaken, and should react to throttle changes pretty quickly. Any tips to setting up the tool correctly?

 

[cj1]

If the manifold converter is original than chances are it is failing given the P0420.
Regarding the O2 sensors, the one before the manifold cat is probably an a/f sensor, in which case follow Tony's operation description.

You may be better off with inexpensive scan tool to check basic engine parameters.

 

[joea]

Thought I had this licked. Changed AF sensor and found a slightly loose intake hose to manifold. But it came back.

Was going to put in a used exhaust manifold/CAT but local yard told me it is illegal in NY state to sell used CATs. Odd. So, before I spring for a new one, how can one isolate if the front or rear is at fault?

BTW, if hunting for used parts, avoid this place: http://www.uneedapart.com/ I landed there from a local yard site and within minutes after submitting my request, my cell phone was bombarded with calls offering a manifold, all with heavy accents. Several emails also. I even got two calls from NIGERIA!. Coincidence? By then I had stopped answering. . Sheesh.

 

[insightbrewery]

Thought I had this licked. Changed AF sensor and found a slightly loose intake hose to manifold. But it came back.

Was going to put in a used exhaust manifold/CAT but local yard told me it is illegal in NY state to sell used CATs. Odd. So, before I spring for a new one, how can one isolate if the front or rear is at fault?

BTW, if hunting for used parts, avoid this place: http://www.uneedapart.com/ I landed there from a local yard site and within minutes after submitting my request, my cell phone was bombarded with calls offering a manifold, all with heavy accents. Several emails also. I even got two calls from NIGERIA!. Coincidence? By then I had stopped answering. . Sheesh.

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