HELP - Can't Pass Smog - Catalyst Won't Reset

[thesabreslicer]

Hey everyone,

I just recently purchased a 2000 Limited (California) from a friend and my first mistake was not getting it smogged right away. Did some electrical work on it (and in the process disconnected the battery), and when I went to smog it a few days later, it failed because the cat monitor was not ready. I drove it about 850 miles after that, went back to smog, and the cat monitor was still not ready.

After that, I found the Toyota Service Bulletin that described how to run the drive cycle for the cat monitor (linked here) and did it as best as I can 4 times. The cat monitor still refused to set.

So this morning I picked up a replacement O2 sensor and swapped it in. I haven't really driven the car since then but we'll see if that helps finally set the monitor. I'll drive it generally and also do a couple of drive cycles to see if that helps.

Barring that working, does anything else have suggestions for what I can do to get the monitor to set? If you need to know any additional info let me know too. Thanks!

 

[jremus]

You can drive that combo of mph/speed 100 times over, but if you have a bad gas cap the monitors still won't reset.

so... check/replace your gas cap. I don't mean "tighten the hell out of it" i mean, try a different gas cap if yours in 20 years old

 

[thesabreslicer]

You can drive that combo of mph/speed 100 times over, but if you have a bad gas cap the monitors still won't reset.

so... check/replace your gas cap. I don't mean "tighten the hell out of it" i mean, try a different gas cap if yours in 20 years old

My evap monitor is fine, it had no problems becoming ready. Would the gas cap still be preventing the cat monitor from being ready?

 

[jremus]

My evap monitor is fine, it had no problems becoming ready. Would the gas cap still be preventing the cat monitor from being ready?

Hmm, well, I can't give definite yes or no.. But I mention the gas cap cuz my situation wasn't too different sounding last Fall.
I took a trip out of state and my battery died at the airport for that 5 days I was gone (door slightly ajar, overhead light on).
I jumped the car, drove home, thought nothing of it. Went to smog it the a day or so later because that was on my list of stuff to do that week. Failed the test.

Point is.. I was throwing cat and evap codes b/c of the battery dying and resetting my ECU. Was told "just drive a while and the codes will clear, come back and retest.."
Put 300 miles + on it over the next week or so, highway and city. Still couldn't clear it for smog-readiness. The guy even took my gas cap off, looked at it, cranked it wayyy down. then he showed me his book and said "take a picture of this drive pattern, do this exactly" and I did. several times. Still couldn't clear it.

but I had a spare gas cap and figured I should try swapping it out. Ran the drive pattern one more, cleared all my codes first-try.

So... long story aside.. I don't know if it's a "yes it totally works" but there are definitely times it seems to be something that simple.

 

[thesabreslicer]

Hmm, well, I can't give definite yes or no.. But I mention the gas cap cuz my situation wasn't too different sounding last Fall.
I took a trip out of state and my battery died at the airport for that 5 days I was gone (door slightly ajar, overhead light on).
I jumped the car, drove home, thought nothing of it. Went to smog it the a day or so later because that was on my list of stuff to do that week. Failed the test.

Point is.. I was throwing cat and evap codes b/c of the battery dying and resetting my ECU. Was told "just drive a while and the codes will clear, come back and retest.."
Put 300 miles + on it over the next week or so, highway and city. Still couldn't clear it for smog-readiness. The guy even took my gas cap off, looked at it, cranked it wayyy down. then he showed me his book and said "take a picture of this drive pattern, do this exactly" and I did. several times. Still couldn't clear it.

but I had a spare gas cap and figured I should try swapping it out. Ran the drive pattern one more, cleared all my codes first-try.

So... long story aside.. I don't know if it's a "yes it totally works" but there are definitely times it seems to be something that simple.

Well I just did another drive cycle (and the first time I drove the car more than a couple miles today) and the cat monitor readied up! So looks like it was just a weird faulty O2 sensor. Thanks for the input though!

 

[jremus]

Well I just did another drive cycle (and the first time I drove the car more than a couple miles today) and the cat monitor readied up! So looks like it was just a weird faulty O2 sensor. Thanks for the input though!

Nice! hey, any problem solved is a win. right? Glad you got it readied for smog!

 

[AntleredRuin]

I was also gonna point to the front O2 sensor.

I live in Texas, which allows 2 'unready' monitors on a pre-2000 vehicle and still pass, but I for the life of me could not net my new Walker Cat to be ready.

I eventually gave up because I got inspected fine, but then later replaced the front O2 sensor for an unrelated issue, and the CAT became ready the next day.

 

[elykrunner]

Have seen your other post on Emissions Monitors not completing. I assume you have looked at the TSB that I referenced earlier in this thread that shows the drive cycles - take careful note of the preconditions. Lots of them for the Evap monitor and the Catalyst monitor won't run if the O2 monitor hasn't previously passed.

Both the Evap and catalyst monitors are two trip DTC's. They set pending codes when they fail the first time which doesn't complete the monitors and doesn't light the CEL...all the preconditions need to be met again and then they need to run/fail a second time to set the DTC (permanent code) and light the CEL. Can your scanner read pending codes? Not all scanners do....If not, you don't have a clear picture on status and all you see is your monitor does not complete. If you clear the code, disconnect the battery or lose voltage to the ECM before the monitor runs/fails a second time, everything starts over again....

Buckaroo

Hi, I am having similar issue with evap and cat not setting. It took 100 miles for the O sensor to come on. I never had a code pop up, so today I tried tripping a code by unplugging the evap sensor, and that didnt work, so I took off the gas cap too. Neither tripped a code. Reading this I would assume it would take 2 drives to make a code appear? Just trying to figure out if my computer is working properly, which I assume it is because the other monitors are ready?

So Far, I replaced the o2 sensors the the throttle position sensor and gas cap with no avail. Last time this happened I replaced the ground from the battery to the body of the car and that fixed it.

 

[Buckaroo]

Hi, I am having similar issue with evap and cat not setting. It took 100 miles for the O sensor to come on. I never had a code pop up, so today I tried tripping a code by unplugging the evap sensor, and that didnt work, so I took off the gas cap too. Neither tripped a code. Reading this I would assume it would take 2 drives to make a code appear? Just trying to figure out if my computer is working properly, which I assume it is because the other monitors are ready?

So Far, I replaced the o2 sensors the the throttle position sensor and gas cap with no avail. Last time this happened I replaced the ground from the battery to the body of the car and that fixed it.

Yes, you need two drive cycles to set the permanent code for the evap or cat and light the CEL. If your code reader reads pending codes, you should be able to see if that is set after one drive cycle although the CEL will not light. Also, these monitors do not run continuously. They only run when the preconditions are satisfied - if the monitor did not run, it would not even set a pending code. Attached the TSB I referenced in my original post as I see my previous link is no longer working.

 

[SocalRunner15]

For a proper drive cycle...does the coolant temp need to go back down to ambient or can you be driving- turn off the car- and have a new 'drive cycle'?

I'm having a heck of a time getting the catalyst monitor to cycle. I have a feeling its my cooler thermostat that doesn't let the car get above 176 during warm up right now. I even tried blocking off the radiator with cardboard....it gets up to 171 only...

 

[phattyduck]

The drive cycle requires the engine temperature to be above 75*C/167*F before the the ECU starts checking cat performance.

-Charlie

 

[SocalRunner15]

The drive cycle requires the engine temperature to be above 75*C/167*F before the the ECU starts checking cat performance.

-Charlie

Based on the instructions i saw....it has to be 176 or higher. So this would mean i can get it up to temp. Turn it off...go through the specific drive cycles and it should then reset?

and if it happens to drop below 176 during the drive cycle, it won't be an issue?

 

[Endlessblockades]

Based on the instructions i saw....it has to be 176 or higher. So this would mean i can get it up to temp. Turn it off...go through the specific drive cycles and it should then reset?

and if it happens to drop below 176 during the drive cycle, it won't be an issue?

I believe the T-Stat opens at 185. I can get down to 183 flying down a mountain on a highway at night but have never seen 176 or lower after warming up. Is that an extreme winter thing?

 

[Sparky 97Runner]

For a proper drive cycle...does the coolant temp need to go back down to ambient or can you be driving- turn off the car- and have a new 'drive cycle'?

I'm having a heck of a time getting the catalyst monitor to cycle. I have a feeling its my cooler thermostat that doesn't let the car get above 176 during warm up right now. I even tried blocking off the radiator with cardboard....it gets up to 171 only...

I have had to do this several times recently and have had no problems resetting with my engine temps at 185* - 192*F. I never let it go back down to ambient between drive cycles. I think running at 171* is way too cool. Why not install a factory thermostat and be done with this? Even the FSM says the thermostat valve opening temp should be between 176* - 183*F.

 

[Endlessblockades]

Oops - I missed the message regarding running a cooler-than-OEM T-Stat.

 

[SocalRunner15]

Oops - I missed the message regarding running a cooler-than-OEM T-Stat.

Yeah...i run a cooler t-stat because my 4r is supercharged, so it helps a bit with keeping temps down...