[bullitt4110]

I recently bought a 2019 ZL1 1LE and I’m needing to have it pass an emissions test to get it registered. The fuel and evap monitors are not becoming ready. The car has headers and the rear o2’s were left out previously so I installed some new o2’s which cleared some “permanent” codes but after 400-500 miles and multiple tanks of fuel and trying to drive at different MPH’s to get them to set nothing has helped. The car does have a flex fuel sensor, could that be the issue? I’ve had cars pass the test in the past with flex sensors but nothing this new. Any suggestions?

[Trochoidal]

Have you completed the drive cycle?

General Motors Driving Cycle

A complete driving cycle should perform diagnostics on all systems. A complete driving cycle can be done in under fifteen minutes.
To perform an OBDII Driving cycle do the following:

Cold Start. In order to be classified as a cold start the engine coolant temperature must be below 50°C (122°F) and within 6°C (11°F) of the ambient air temperature at startup. Do not leave the key on prior to the cold start or the heated oxygen sensor diagnostic may not run.

Idle. The engine must be run for two and a half minutes with the air conditioner on and rear defroster on. The more electrical load you can apply the better. This will test the O2 heater, Passive Air, Purge "No Flow", Misfire and if closed loop is achieved, Fuel Trim.

Accelerate. Turn off the air conditioner and all the other loads and apply half throttle until 88km/hr (55mph) is reached. During this time the Misfire, Fuel Trim, and Purge Flow diagnostics will be performed.

Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for 3 minutes. During this time the O2 response, air Intrusive, EGR, Purge, Misfire, and Fuel Trim diagnostics will be performed.

Decelerate. Let off the accelerator pedal. Do not shift, touch the brake or clutch. It is important to let the vehicle coast along gradually slowing down to 32km/hr (20 mph). During this time the EGR, Purge and Fuel Trim diagnostics will be performed.

Accelerate. Accelerate at 3/4 throttle until 88-96 km/hr (55-60mph). This will perform the same diagnostics as in step 3.

Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for five minutes. During this time, in addition to the diagnostics performed in step 4, the catalyst monitor diagnostics will be performed. If the catalyst is marginal or the battery has been disconnected, it may take 5 complete driving cycles to determine the state of the catalyst.

Decelerate. This will perform the same diagnostics as in step 5. Again, don't press the clutch or brakes or shift gears.

[airtroop01]

Headers typically are not going to pass the visual in CA… unless you have someone willing to overlook it. Does it have a tune as well?

[bullitt4110]

Originally Posted by airtroop01

Headers typically are not going to pass the visual in CA… unless you have someone willing to overlook it. Does it have a tune as well?

I’m aware.

But the monitors finally set, just took more driving

[sanchizzlle]

A bit late but posting in case anyone else comes across this thread.

I've been trying to pass CA smog and followed the above drive cycle instructions to no avail. Found the section in the 2017-8 service manual where it describes the I/M system set procedure. The cliff notes are below:

Cold Start Requirements
* 11-18 volts
* Baro pressure
* More than 75 kPa
* Coolant temp, intake temp & ambient
* 4-30C or 39-86F
* Difference between IAT & ECT is <= 6C or 10.8F
* Fuel
* 15-85%

If ignition is turned ON wait at least 5 minutes for O2 sensors to cool. Once engine has started do NOT turn off for remainder of test.

When idling DO NOT touch the throttle.

1. Meet cold start requirements
2. EVAP & O2 Heater I/M system status should say YES
3. Turn OFF all accessories (AC & other electrical loads)
4. Set parking brake & put in neutral
5. Start & idle engine for at least 2 mins and until 65C or 148F is achieved
6. With vehicle in neutral run engine for 6.5 minutes meeting the following:
- MAF 4-30 g/s
- Engine speed 1-2k RPM
7. Return to idle for 1 minute
8. Operate vehicle for 2 minutes meeting the following:
- TPS (throttle) more than 2%
- MAF 15-30 g/s
- RPM 1.2-2K RPM
9. Release accelerator and return to idling in neutral for 2 mins
10. Quickly press pedal until TPS is > 8% and return to idle
- Repeat 3 times
11. Idle for another 2 minutes
12. Drive at 15 mph or slower for 2 mins
13. Continue driving at least 5.5 miles between 28-70 MPH
- Go at least 50 mph once
14. Release accelerator for at least 2 seconds
15. Depress pedal until TPS is increased by 3-20% for 1 minute
16. Stop vehicle and idle for 2 minutes with clutch depressed
17. Apply parking brake and release clutch
18. Turn off the ignition and exit the vehicle, do not disturb vehicle for 60 minutes
19. Check I/M status if all YES you’re good
* If EVAP is NO turn off ignition for 17 hours and perform cold start and do steps 10-16

This differs quite a bit from the "standard" GM drive cycle procedure. Going to try this out tonight and see if I can get the last 2 systems to show "completed." If anyone wants a pdf copy of the section from the manual PM me.

[CalgaryZL1]

Originally Posted by sanchizzlle

A bit late but posting in case anyone else comes across this thread.

I've been trying to pass CA smog and followed the above drive cycle instructions to no avail. Found the section in the 2017-8 service manual where it describes the I/M system set procedure. The cliff notes are below:

Cold Start Requirements
* 11-18 volts
* Baro pressure
* More than 75 kPa
* Coolant temp, intake temp & ambient
* 4-30C or 39-86F
* Difference between IAT & ECT is <= 6C or 10.8F
* Fuel
* 15-85%

If ignition is turned ON wait at least 5 minutes for O2 sensors to cool. Once engine has started do NOT turn off for remainder of test.

When idling DO NOT touch the throttle.

1. Meet cold start requirements
2. EVAP & O2 Heater I/M system status should say YES
3. Turn OFF all accessories (AC & other electrical loads)
4. Set parking brake & put in neutral
5. Start & idle engine for at least 2 mins and until 65C or 148F is achieved
6. With vehicle in neutral run engine for 6.5 minutes meeting the following:
- MAF 4-30 g/s
- Engine speed 1-2k RPM
7. Return to idle for 1 minute
8. Operate vehicle for 2 minutes meeting the following:
- TPS (throttle) more than 2%
- MAF 15-30 g/s
- RPM 1.2-2K RPM
9. Release accelerator and return to idling in neutral for 2 mins
10. Quickly press pedal until TPS is > 8% and return to idle
- Repeat 3 times
11. Idle for another 2 minutes
12. Drive at 15 mph or slower for 2 mins
13. Continue driving at least 5.5 miles between 28-70 MPH
- Go at least 50 mph once
14. Release accelerator for at least 2 seconds
15. Depress pedal until TPS is increased by 3-20% for 1 minute
16. Stop vehicle and idle for 2 minutes with clutch depressed
17. Apply parking brake and release clutch
18. Turn off the ignition and exit the vehicle, do not disturb vehicle for 60 minutes
19. Check I/M status if all YES you’re good
* If EVAP is NO turn off ignition for 17 hours and perform cold start and do steps 10-16

This differs quite a bit from the "standard" GM drive cycle procedure. Going to try this out tonight and see if I can get the last 2 systems to show "completed." If anyone wants a pdf copy of the section from the manual PM me.

Well, that’s almost easier than changing the transmission fluid. Must’ve been the same engineer working on that one.

[Dynamical]

true though!


Yep, the evap can be a total bitch. Here in CT they will make an exception with the evap because they know its a bitch. My truck had the same issue.

[carguy55]

what does "I/M system" mean? I'd like a pdf copy of this

[Gunkk]

Inspection/Maintenance

[chachasama]

I bought a 2023 SS convertible few days ago from WA to CA, so I have a same problem.
I found "Inspection/Maintenance Complete System Set Procedure" in Service manual.
And related service bulletin "Information for New Vehicles with Less than 1,000 Miles that May Not Pass California Smog Inspection or Smog Inspection in Other States."

Are there any cases where HO2S monitoring was completed even before 400 miles?

[turbo2ltr]

I have an 18 and the EVAP test is absolutely killing me. I'm 4 months late on my registration because I can't get it to run. Currently driving around on a 30 day temp that expires in 2 days and I won't be able to get another for a year. And all this driving around my 6000 mile mint condition all original completely stock car earned me a cracked windshield thanks to some moron that decided he didn't want to exit the freeway and cut the gore point. Really not happy about this whole situation.

[chachasama]

Some updates.

After 400 miles, the EVAP monitor was completed, but HO2S still needed to be completed. I drove 500 miles in total and still have yet to change.

So, I followed the instructions in Information for New Vehicles with Less than 1,000 Miles that May Not Pass California Smog Inspection or Smog Inspection in Other States.

3. In California, the customer can call 1-800-622-7733 to make an appointment with the California Bureau of Automotive Repair (BAR) Referee Scheduling Center in order to get a waiver from the Oxygen Sensor Monitor Complete requirement.

I called, made a book, and went to the CA smog referee center. After 15 minutes, I paid $8.25 for my smog check certification, which they electronically transmitted to the DMV. Finally, I got the license plate today.

It only allows less than 1000 miles of vehicles and purchased out-of-state.

[jebfour]

Bumping this old thread...

I did the unthinkable and disconnected the battery and now I have catalyst and O2 sensor are incomplete / not ready. After doing another drive cycle today, now the fuel sensor monitor shows as incomplete / not ready (??). This is beyond ridiculous. The car has less than 7K miles.

Just because I'm at my wits end with this thing, I have a few questions. They may be stupid, but I'm going to ask them anyway.

- During the drive cycle: After doing a cold start and letting it idle for 2-1/2 minutes, I have to drive over to a place about 5-7 miles away so that I can hold 55 MPH for three minutes. Could that short drive in-between the two steps be causing an issue?

- Can I use cruise control to hold exactly 55 MPH or will that cause an issue? I wouldn't think so but as frustrating as this has been, I wouldn't be surprised.

- Is there really nothing the dealer can do to get these ready? It's not like GM goes through all this nonsense before putting the car on the lot.

[arpad_m]

Originally Posted by jebfour

Bumping this old thread...

I did the unthinkable and disconnected the battery and now I have catalyst and O2 sensor are incomplete / not ready. After doing another drive cycle today, now the fuel sensor monitor shows as incomplete / not ready (??). This is beyond ridiculous. The car has less than 7K miles.

Just because I'm at my wits end with this thing, I have a few questions. They may be stupid, but I'm going to ask them anyway.

- During the drive cycle: After doing a cold start and letting it idle for 2-1/2 minutes, I have to drive over to a place about 5-7 miles away so that I can hold 55 MPH for three minutes. Could that short drive in-between the two steps be causing an issue?

- Can I use cruise control to hold exactly 55 MPH or will that cause an issue? I wouldn't think so but as frustrating as this has been, I wouldn't be surprised.

- Is there really nothing the dealer can do to get these ready? It's not like GM goes through all this nonsense before putting the car on the lot.

Here is an older, but hopefully still valid article about the GM driving cycle: https://www.obd-codes.com/trouble_co...ving-cycle.php. Try this method and see if readiness monitors are finally satisfied.