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Discussion Starter · #1 ·
Now that the Volt has been on the road a few years, vehicle emission testing questions from owners are cropping up. Here are some answers to common questions.

Short answer version
A long version with more details is in a following post for those who need more than an hors d'oeuvre to feel full. :)


Does my Volt's gasoline engine require emission testing?
Probably, if your area requires gasoline-powered cars to be tested. The Volt has a gasoline engine.

Can my Volt fail the test?
Yes.

What conditions can cause a failed emission test?
No/rare gasoline use and/or disconnected/replaced 12V battery.

Why would a rarely used gasoline engine fail an emissions test?
Because the car has insufficient emission diagnostic data to pass the test.

Why would disconnecting the Volt's 12V battery cause an emission testing issue?
Because the car has insufficient emission diagnostic data to pass the test.

Why would disconnecting the Volt's 12V battery cause an emission testing issue?
It wipes the car's emission diagnostic data. No data = fail.

What should I do if my Volt's battery was recently disconnected or I never/rarely use gas?
Prior to the test, drive only on gasoline for three days, with the car off for 8 hours in between.

What should I do if my Volt still fails the emissions test?
Repeat the steps above.
 

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Discussion Starter · #2 · (Edited)
Long Answer Version (compiled from various GM-Volt posts)

Does my Volt's gasoline engine require emission testing?
Maybe. It depends on your state laws and where you live. Many states or regions treat the Volt like any other gasoline-powered car when it comes to emission testing.

Can my Volt fail the test?
Yes, it could for a few Volt drivers. The most likely cause during the first 10 years would simply be a lack of emissions diagnostic data, rather than an actual emissions equipment failure. If you drive a Volt like most, you are using the gas engine 10%-40% of the time and would likely not have a failed emission test due to lack of emissions diagnostic data.

What conditions can cause a failed emission test?
1) You have never or rarely used the gasoline engine, or
2) You recently had the 12V battery disconnected or replaced, or
3) Old/faulty equipment or an out of tune engine (both unlikely during the Volt's first 10 years I think)

Remember, very, very few Volts never use gas or haven't used gas since a 12V battery issue. If you drive a Volt like most, you are using the gas engine 10%-40% of the time and would likely not have a failed emission test due to 1 or 2 above.

But if you are one of the fortunate Volt owners who rarely use gasoline, or an unfortunate Volt owner who just had the battery replaced/disconnected, then it's possible you'll need to drive on gasoline for a while to rest the car's emission diagnostics in order to pass the emissions test.

Why would a rarely used engine result in a failed emissions test?
Yes, it's counter-intuitive and perhaps even silly that a car that rarely uses gasoline would fail an emissions test. But most (all?) emissions tests today are done by simply plugging into the car's OBDII port and reading the car's internal emissions diagnostics for the gasoline engine.

If your car's engine has never run, or rarely run there simply may not be enough info to pass the car. In that case, "incomplete" get's a failing grade same as a car with an out of tune engine or faulty oxygen sensor or the like.

Why would disconnecting the Volt's 12V battery cause an emission testing issue?
The engine emissions diagnostics history gets wiped out by a battery disconnect/replacement, so there is no data for determining whether the car should pass or not. Same as the topic above, an "incomplete" get's a failing grade same as a car with an out of tune engine or faulty oxygen sensor. This prevents people from trying to trick the emission testing by clearing emissions trouble codes via a battery disconnect.

If the car's 12V battery was recently replaced or disconnected, and your gasoline engine has been used rarely or not all since then, the Volt will likely fail the test due to insufficient emissions diagnostic info rather than due to emission trouble codes.

The Volt is not special or being singled out, it would be the same with any car since 1996 with OBDII and a dead/disconnected/replaced battery. The emissions diagnostics built into the car have to be performed by running the engine (a.k.a, the Volt's range extender) for a set amount of time and situations in order to ensure all the mandated emissions equipment on the car work. The Volt's engine and emission equipment is the same as any other gasoline engined car in this regard.

What should I do if my Volt's battery was recently disconnected or I never/rarely use gas?
Before the test, drive it using the gasoline engine for long enough to reset all the internal emission diagnostic data.

How long and under what conditions should I drive on gasoline?
This seems to be the tricky part. The manual says drive on gas for two days before the inspection, so do as the manual suggests and maybe add a day for good measure, leaving the car sit off for 8 hours in between. But some want exact specifics, which, like many things Volt, are not always so black and white. There isn't a recipe like "x miles/hours at 35 MPH, followed by y miles /hour at 60 MPH, etc".

Some member and dealer suggestions (but see the minimum requirements question below):

  • "The fuel maintenance mode (every 6 weeks ) and 1 tank a year burn off (forced to prevent stale fuel) should be more than enough data for the ready flag to be set for OBDII emissions check."
  • "Just run a tank or 2 of gas through it".
  • "Run the battery down to one bar and put it into mountain mode for a 25-30 mile trip. Then shut off the car and leave it undisturbed for about 8 hours or overnight. before restarting, Repeat a couple of times."
  • "Drive 10 minutes on a highway with the engine on"
  • "Use Mountain Mode for three or more days before the inspection, and don't recharge the car for that period".
  • "A typical car it takes 75 miles driving for the odb to be reset after a battery disconnect"
  • "Its impossible to tell exactly how long it will take to clear all the monitors. It depends on the individual car and even the drivers driving style or route. To clear all of them require different drivings conditions and sometimes multiple cold starts and multiple times reaching operating temperature."

What are the minimum requirements for resetting the emission diagnostics?
We do have a minimum requirements after a 12v battery failure/disconnect to set the I/M flags that some states retrieve from the Volt's ECM during certain emissions tests that still use the IM240 model.

The car's control system will need to observe

  1. At least one cold start of ICE ("cold" in this case just basically means the engine is at ambient air temperature conditions between 39-114F).
  2. Then ICE will need to run long enough to get the oxygen sensors hot enough to get into "closed loop" and validate the catalytic converter functionality as well as permit the fuel trims to "trim out" to stable values.
  3. During the run period the software routine must observe a vehicle speed of at least 25mph and an engine RPM of at least 1800 at least once.
  4. Then the car must be shut off for at least 8 hours straight in order to trigger certain EVAP "natural vacuum" diagnostics.

There are a few more defined parameters but typically all easily met with an engine running for at least 10-15 minutes or so.

But without a scan tool that permits you to observe IF the I/M flags are actually "set"- it can be a bit of a guessing game.

So depending on your state's penalties or repercussions for failing you might want to consider just doing one leg of your daily commute in Charge Sustaining (gasoline) mode, preferably on a day that you know you will be able to leave the car OFF for at least 8 hours straight after reaching your destination. Very good chance that the I/M flags will have been set under those conditions and will pass if retested.

http://gm-volt.com/forum/showthread...ns-on-MA-State-Inspection&p=143398#post143398

What happens if I follow the minimum requirements above and still fail?
Drive the car a few more days on gasoline alone. Or, see this advice:

Once a vehicle has failed a the test they shouldn't just be arbitrarily re-testing to see if it passes. Once a car had failed the "readiness" test they should first be following the standardized "System Check-Vehicle" process to insure power-mode states, proper network traffic, and that NO DTCs are set in ANY systems BEFORE following GM document #2545519 Inspection/Maintenance System Check which details specifics of the I/M Inspection Maintenance process used on the Volt and references another GM document #2547681 "Inspection/Maintenance (I/M) System Set Procedure" to assist in establishing the specific road test requirements in order to meet all the necessary enable criteria. This process designed to validate and confirm ALL of the various I/M readiness flags are "set" PRIOR TO performing any emissions re-test.

There are just TOO MANY fussy parameters for the average owner to verify and perform this road test without the service manual or without the availability of a proper scan tool to observe the I/M flag states.
For instance you said you did a "cold start" For the purpose of this test a cold start means the engine coolant temperature value is within 5C degrees from the ambient air temperature sensor value. How did you verify that for YOUR cold start?

Then there are other "fussy" parameters such as fuel levels MUST be within 10-90% etc etc .

THEN if the readiness flags ARE STILL NOT properly setting after accurately completing this detailed roadtest the technician is then instructed to utilize GM document #2541072 "Inspection/Maintenance I/M System DTC Table" in order to determine which specific DTC chart/s are to be utilized next. Specifically those that are responsible for the "not ready" status. Only these DTC specific documents provide the necessary detail and data required to determine what exactly what might be preventing their diagnostics from properly completing their routines.
ALL this needs to be done with a depleted battery, operating in extended range (CS) mode of course.

Try giving your dealership these document numbers and advise them to attempt re-establish the I/M readiness flags (since it apparently was THEIR service that resulted in them being wiped in the first place)
It wont be easy for you or any other owner to perform these detailed road tests without a lot of frustration should they not result in a PASS.

Finally let me reiterate what I had previously stated in the other "Failed in MA" thread http://gm-volt.com/forum/showthread.php?42745-Failed-MA-State-Inspection&p=564497#post564497

This is not a Volt issue.
This issue is really no different for ANY car with an internal combustion engine .
They all work this way when it comes to these EPA legislated OBDII diagnostics (since 1996 in fact)
The only issue with the Volt is in order to a) have emissions and b) test the emissions self-diagnostic systems the ENGINE MUST RUN!
Since the Volt operates primarily as electric, this goes against the grain for some people and while it may appear as counter intuitive, since it has an ICE then it MUST be treated as such in order to remain in compliance with OBDII.
http://gm-volt.com/forum/showthread...tion-Not-Enough-Gas-Used.&p=955666#post955666


Reference Posts
http://gm-volt.com/forum/showthread.php?42745-Failed-MA-State-Inspection
http://gm-volt.com/forum/showthread.php?71105-My-Volt-Failed-State-Inspection-Not-Enough-Gas-Used.
 

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That's a great sets of FAQ's thanks for summing up all the items from some long posts.

In TEXAS the car registration in NO place says VOLT or electric or hybrid - only says FUEL TYPE GAS
the VIN number is there and CHEVY/4H as make - 3711 weight and a bill due of $62.75 ( and $5 min if I WANT to donate to stat parks)
 

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Discussion Starter · #6 ·
Can you get it done at the Dealer to prevent hassles?

MrEnergyCzar
Some auto repair shops are now authorized to perform these test. It depends on the state/testing area.
 

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I guess my old trick of putting 1/3 tank of E-85 in the car and driving on the freeway for 30 minutes isn't going to work with the Volt, like it did with my old Chevy Tracker.
 

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This link http://www.dmv.ca.gov/vr/smogfaq.htm#BM2543 states the following: Does my vehicle qualify for a smog exemption?

Smog inspections are required unless your vehicle is:
• Hybrid
• Gasoline powered 1975 year model or older
• Diesel powered 1997 year model and older or with a Gross Vehicle Weight rating (GVWR) of more than 14,000 lbs
• Electric
• Natural gas powered with a GVWR rating of more than 14,000 lbs.
• Motorcycle
• Trailer
(In Cali. the strictest standards in the country the Volt is exempt from emissions tests)I don't see a class on this generic list though as the Volt is a REV, although some call it a hybrid, some an electric some a plug in hybrid.
All electric vehicles use electricity from generators. Most of the generators are stationary- coal, PV, CSP, wind, nuclear, CNG, CHP, geo, etc generation plants. The Volt benefits from both stationary and on board generation.
 

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Discussion Starter · #9 ·

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I took my Volt in for state inspection (Tx) and had a different experience than listed in the faq. The inspector wanted to start the engine. I told him the engine won't start whlile the battery has life (2012= no hold mode).

I asked him why the engine had to run and he said that his computer needed to have the engine revved in neutral. I told him that the engine won't rev in neutral anyway.

If this is true there is no way to get a Volt to test for emissions which I can't believe. Maybe this guy has obsolete testing equipment or he is poorly trained.

Folks in Texas, how did your inspection experience go?
 

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You can always just open the hood . I have never tried MM when not moving.
With the right battery level will that change engine speed while in park ?
 

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In AZ new cars are exempt for 5 years, the an OBD test is done after the 5 years on anything newer than 1996. Looks like the 2011 purchased in May of 2011 will needs another couple of years before it is required. Hmmm wonder how that will work with the 2 year renewals?
 

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I took my Volt in for state inspection (Tx) and had a different experience than listed in the faq. The inspector wanted to start the engine. I told him the engine won't start whlile the battery has life (2012= no hold mode).

I asked him why the engine had to run and he said that his computer needed to have the engine revved in neutral. I told him that the engine won't rev in neutral anyway.

If this is true there is no way to get a Volt to test for emissions which I can't believe. Maybe this guy has obsolete testing equipment or he is poorly trained.

Folks in Texas, how did your inspection experience go?
I'm kind of curious to as I am looking at a Volt. I also used to be a state inspector here in Texas for a VW dealer. The way the test worked was that the computer was plugged into the OBD port with the car running. It ran its tests (there is no requirement to rev the engine or anything like that) while plugged in and then if it passed, it was disconnected. Then we hooked up a gas cap tester to the gas cap to ensure that it sealed.
 

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You can always just open the hood.
+1.

If possible, it would be a good idea to add this detail to the original post's FAQ list.

I just had my first emissions test done and I was surprised when they told me the engine needed to be running. Fortunately I remembered the popped hood trick. This was the first Volt that this shop had tested so they were unaware.
 

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Why did they think the engine needed to be running to check the sensor ready status? Here in Illinois I never had to start the engine for the emissions test. Oh, I see you're from IL too.
 

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I took my Volt in for state inspection (Tx) and had a different experience than listed in the faq. The inspector wanted to start the engine. I told him the engine won't start whlile the battery has life (2012= no hold mode).

I asked him why the engine had to run and he said that his computer needed to have the engine revved in neutral. I told him that the engine won't rev in neutral anyway.

If this is true there is no way to get a Volt to test for emissions which I can't believe. Maybe this guy has obsolete testing equipment or he is poorly trained.

Folks in Texas, how did your inspection experience go?
Pop the hood and shift to neutral and set the parking brake ( after shifting to neutral! ) the engine will rev with the gas pedal, not like a regular car, but will go from idle to a higher rpm range and back.

I know my 2015 did this as I showed it off to some of my coworkers who wanted to see the engine and know how it worked.
 
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