I have an old 2000 Camry car that died in storage and so I replaced the battery 4 months ago. That reset all the monitors. Since bringing it back up it also had a check engine light which required me to replace the coolant thermostat.

I replaced the thermostat a few weeks ago.

Recently I did an OBD scan and it shows that "catalyst test not ready". I'm assuming due to the thermostat issue, I have not been able to get the data for the catalyst converter. All other test passed

Since then, I've driven a couple hundred miles but the OBD scan hasn't changed.

Is the catalyst busted? Is it worth replacing? Other than that, the car runs fine.

I have a smog test coming up. Is there a way to fix this and get the test passed quickly?

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    Welcome to Motor Vehicle Maintenance & Repair! Jun 27, 2019 at 21:29

2 Answers 2


You need to get through the drive cycle for your Camry. Following these steps exactly should get you there (as found on this website):

2000 Toyota Camry Drive Cycle (Engine 1MZ-FE & 5S-FE - CA Emissions Certified)

Begin by: (Make sure you have between 1/4 and 3/4 fuel in the gas tank. The EVAP test will not run while your Toyota has a full tank of gas or the gas tank is near empty). Ensure there are no pending or active trouble codes and that the check engine light is not on.

A. Start the engine and allow it to idle for 2 minutes or more.

B. Drive the vehicle at 40-70 mph or more for at least 3 minutes. Be sure to maintain engine speed between 900 and 3,200 rpm.

C. Stop the vehicle and allow the engine to idle for 10 seconds or more.

D. Drive the vehicle at 25 mph for at least 40 seconds or more. Be sure to maintain engine speed above 900 rpm.

E. Stop the vehicle and allow the engine to idle for 10 seconds or more.

F. Perform steps “D” and “E” ten times.

G. Drive the vehicle allowing speed to fluctuate between 35-45 mph for about 16 minutes.

If readiness status of all monitors do not switch to “complete,” ensure preconditions are met, turn the ignition switch OFF, then repeat steps “A” through “G.”

What it comes down to is, you haven't done something right here. One or more of the steps need to be finished. Doing them in order and as specified should get you there.

  • thanks! I actually tried to do this before, but it was very difficult to do this. For example between step F and G, I would need to drive to a highway to have uninterrupted driving. In between that I might stop at a few stoplights and drive slowly for a while. Is there any place that can allow me to do this cycle in a shop?
    – mugetsu
    Jun 27, 2019 at 21:36
  • Any place with a treadmill ... but really, you just need a long country road to make it happen. I realize it's a PITB, but it's what Toyota decided you had to do to complete the drive cycle. Make sure you follow the "pre steps" before you start as well. They are important. (The "Begin by:" section at the beginning.) Jun 27, 2019 at 22:04
  • @Paulster2 is there a way to simplify this cycle if I only need the cat test? Evap has already passed
    – mugetsu
    Jun 27, 2019 at 22:11
  • Who knows what you missed or did incorrectly. To get it done, you've got to go through it. Like I said, it can be a PITB, but in order to pass it, that's what has to be done. Jun 27, 2019 at 22:24

Paulster's answer is correct.

BUT . . . I would suggest between steps C and D, that you take your foot off the throttle and coast down as long as you can (you are still going to need a long no-traffic highway ... please be safe).

This makes the exhaust go very lean, and tests the OSC or "Oxygen Storage Capacity" and the honeycomb matrix heat retention of the cat.

I know for a fact this can help on many cars, and I've even done it on Camrys. The technique is specifically to address the cat monitor.

Also, I'd add prior to step A, the car needs to be stone cold (overnight sitting). You can't have driven it a half hour ago. IAT Intake Air Temp and ECT Engine Coolant Temp sensors need to be very close when starting. This prerequisite, among others (e.g. gas tank level 25%-75% for Evap monitor) were decided a long time ago and are not usually OEM brand-specific. Also, check pending/active codes with key in run position, but do not start the vehicle. Clear the codes (if any) before you start the engine. Starting the engine may take you out of the temperature prerequisites, which means starting over.

Those prerequisites MUST be met for the specific monitor test to even run. It won't let you start with a hot engine (and hot cat).

You could try my trick a few times to see if it gets rid of your cat monitor. If not, Paulster's answer is the only path.

All the other steps are correct, but I'm suggesting this strategy to get the cat monitor to pass.

If your scan tool has a "monitor readiness" mode, it's fine to leave it plugged into the OBD II port while driving - it won't affect (or effect) any clearance of monitors.

It's not the amount you drive, it's the specific driving pattern that allows the test(s) to complete. Some cars are much trickier than others - when I worked at an independent across from a Subaru dealer, we inspected all their new cars just prior to delivery. It took 600 miles of driving a brand-new WRX STI in a very specific way to get the monitors to clear and issue a NY state emissions sticker. I was delighted to get paid for this "work", and I surprisingly didn't leave a scratch on the vehicle. Dealer and customer were not so thrilled, and they ended up discounting an additional $1000 to appease the situation.

You could also move to New York State, which allows 1996-2000 model-year vehicles to pass emissions with TWO monitors incomplete, and 2001-20?? vehicles to have ONE monitor incomplete. I think it's ALL complete now, but I don't know the cutoff year. That's a joke; it would be far cheaper to buy a new car . . .

Good luck!

On Edit:

Here's some additional information for a "generic" drive cycle. Paulster's answer is more specific, but this does have some general information that might help:

When a specific drive cycle is not known, or drive cycle information is not available from an owner's manual, the generic cycle described below may assist with resetting your vehicle's monitors. However, this generic cycle may not work for all vehicles.

IMPORTANT: If you choose to use the generic drive cycle below, you must obey all traffic laws and drive in a safe manner. Also, be sure the required preconditions are met prior to performing the drive cycle.

The OBDII drive cycle begins with a cold start (coolant temperature below 122 degrees F and the coolant and air temperature sensors within 11 degrees of each other). The ignition key must not be left on prior to the cold start – otherwise the heated oxygen sensor diagnostic may not run.

As soon as the engine starts, idle the engine in drive for two and one-half minutes, with the air conditioning (A/C) and rear defrost turned on, if equipped. Turn the A/C and rear defrost off, and accelerate to 55 mph under moderate, constant acceleration. Hold at a steady speed of 55 mph for three minutes. Decelerate (coast down) to 20 mph without braking (or depressing the clutch for manual transmissions). Accelerate again back to 55 to 60 mph. Hold at a steady speed of 55 to 60 mph for five minutes. Decelerate (coast down) to a stop without braking.

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