Catalyst monitor not ready

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I need to smog a 2000 Cavalier that has been sitting for 3 years. Battery died, so all of the OBD2 monitors reset themselves, and I can't even go for a smog check until they all show ready. Installed a new battery, changed the fluids, and I've driven the car over 100 miles so far, on lots of rural roads with speeds between 50-60 mph which I've read is ideal for getting this monitor to run. Still showing "not ready" using scan tool.

There are no codes, either pending or active, however after looking online and poking around in the "mode 6" data, there is a "lean to rich sensor threshold voltage" test that consistently comes up failed, with a voltage lower than the minimum value shown. Am I barking up the wrong tree by assuming my oxygen sensors need to be replaced, and this is what's preventing the catalyst test from finishing? They are at least 10 years old as I have not changed them since I bought the car.
 
It may not be enough drive cycles. Just putting miles on it is not enough. You may need more ignition off/on drive cycles rather than just miles.
 
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You're almost there! It seems that it can take as many as 5 unique drive cycles.

I found this for Chevrolet vehicles, it may help:

"The following is a CHEVROLET OBDII Drive Cycle Pattern. (Obey all traffic laws while performing drive cycles. Perform acceleration steps only on highways)

COLD START: Begin from Cold Start, and ignition key in OFF position for at least 1 hour. Insure fuel tank is between 1/4 and 3/4 full. Engine coolant temperature must be below 122°F and within 11°F of the ambient air temperature. Do not leave the key on prior to the cold start or the heated oxygen sensor diagnostic may not run.

IDLE TIME: Run engine (do not drive) for 2 1/2 minutes with the air conditioner on and rear defroster on. During this period the ECU will be running the Oxygen Sensor Heater self-test, Air Injection System Passive Air test, EVAP Purge "No Flow" test, Misfire Detection.

ACCELERATE: Turn off the air conditioner and rear defroster and begin driving. As soon as possible apply half throttle until 55mph is reached. The ECU will now run self-tests on the Misfire Detection, Fuel Trim, and EVAP Purge Flow.

HOLD STEADY: Now hold your speed steady at 55mph for three minutes. During this time the Oxygen Sensor O2 response, Air Intrusive (AIS System), EGR Flow, Purge Valve, Misfire Detection, and Fuel Trim diagnostics will be performed.

DECELERATE: During this step you want to slowly let off the accelerator pedal. Do not brake or shift in order to slow down (don't press the clutch if equipped). It is important to let the vehicle coast along gradually slowing down to 20 mph. The ECU will once again self-test the EGR System, EVAP Purge System and Long Term Fuel Trims.

ACCELERATE: Go ahead and accelerate again at 3/4 throttle until 55-60mph is reached. This will perform the same self tests as during the first acceleration step.

HOLD STEADY: Hold steady speed once again. This time at 55mph for five minutes. During this time, in addition to running the self-tests as during the first HOLD STEADY step, the ECU will perform the catalyst monitor diagnostics. If the catalyst (Catalytic Converter) is marginal or the battery has been disconnected, it may take 5 complete driving cycles to determine the state of the catalyst,or in order to Complete the CAT Monitor.

DECELERATE: This will perform the same diagnostics as in the first Deceleration. Remember not to press the brakes or shift gears (don't press the clutch if equipped).

HOW TO COMPLETE INDIVIDUAL MONITORS

Catalyst Monitor (CAT):

Prerequisite: No trouble codes present, Intake Air Temperature (IAT) above 32 Degrees (F), Engine Coolant Temperature (ECT) is above 167 Degrees (F); Mass Air Flow sensor is indicating greater than 15 gm/s, engine load is below 63% and steady, engine speed is below 3000 RPM.

1. Idle vehicle 5 minutes (achieve closed loop)

2. Drive 5 min at steady speed above 55 mph

3. Drive 2 min at steady 40 mph

4. Drive 2 min at steady 55 mph

EGR Monitor (EGR):

Prerequisite: No trouble codes present, Engine Coolant Temperature (ECT) is above 75 Degrees (F); barometric pressure (BARO) above 72kPa.

1. Idle vehicle 5 minutes (achieve closed loop)

2. Accelerate and drive for 1 min at steady speed above 50 mph

3. Slow vehicle down to 20 mph. Do not use brake clutch, or shift gears.

4. Repeat steps two and three 5 times.

GM and Chevy run their EGR monitor during the deceleration portion of the drive cycle.

Evaporative Monitor (EVAP):

Prerequisite: No trouble codes present, Fuel tank between 1/4 and 3/4 full.

1. Drive 5 min at steady speed between 30 and 60 mph

2. Stop vehicle and idle engine for 4 minutes.

3. Turn engine off. Remove ignition key.

The ECU will run the EVAP Monitor once the engine has been shut down and ignition turned off.

O2 Sensor Monitor (O2):

Prerequisite: No trouble codes present, Intake Air Temperature (IAT) above 32 Degrees (F); Engine Control Temperature (ECT) is above 167 Degrees (F)

1. Idle vehicle 4 minutes (achieve closed loop)

2. Drive 3 min at steady speed above 50 mph

3. Drive 2 min at steady 40 mph

4. Drive 2 min at steady 50 mph "
 
To put it in perspective, I have a car I'm trying to get it to pass and I'm having monitor issues like you. When I showed up for inspection I had three monitors not ready from having the battery changed three months ago! That's been three months of driving and the monitors haven't set. This car is only driven in short trips.

The day after I failed the test I drove on highway trying to simulate drive cycles and as soon as I got back home and checked some of the monitors (like CAT) were ready, just from a single trip.
 
For a 2000 and up, you're only allowed to have the EVAP monitor not ready. For a 1999 and below, you're allowed any two not ready. Extremely annoying, since the only way to get it to be ready is to drive a vehicle with incomplete registration. I really hope I don't have to do that for three months...

Also, anyone know anything about the failed mode 6 test results? There are also a few tests in there with status "incomplete or dependent test failed," whihch is what leads me to believe I might need to fix my 02 issues first, though it's weird it wouldn't have set a CEL if that's the case. I might replace the sensors anyways as general maintenance; they're cheap and I did that on my wife's old car and she gained about 5 mpg instantly. No CEL in her case either, and I have no idea about monitors.
 
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Catalyst monitors are almost impossible to get "ready" but the good news is that two monitors can be "not ready" and still pass
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Originally Posted By: Anduril
Not since 2015 in the People's Republic of California
frown.gif

Ca does allow 1 unset monitor. it can only be the evap one. Got the wifes tahoe smogged last week with only 6 monitors ready.
 
Update: The guy who said it takes 5 trips was exactly right. Drove again today (took a different route, freeway this time, not sure it mattered) and ended with a completed catalyst monitor.
 
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