CARB Requirements
Engine Change Guidelines

OVERVIEW
Engine changes continue to present problems and challenges to car owners and technicians. Here are some tips to keep you and your customers on the straight and narrow.
Our recommendation is to rebuild and reinstall the original engine, transmission, and emission control configuration.
When rebuilding an engine, it must be rebuilt to the original equipment specifications. However, if you do decide to change the engine, these guidelines must be observed to ensure that the vehicle will be eligible for smog certification or registration.
Remember, these are guidelines for performing engine changes – not certification procedures. All exhaust emission controlled vehicles with engine changes must be inspected by an official referee station and must have a Bureau of Automotive Repair (BAR) Vehicle Identification Label affixed to the doorpost.
Remember also, state and federal anti–tampering laws generally prohibit any modification to the vehicle's original emission control system configuration as certified by the manufacturer. And, Section 3362.1 of the California Code of Regulations prohibits any engine change that degrades the effectiveness of a vehicle's emission control system.

CALIFORNIA CERTIFICATION
A federal Environmental Protection Agency (EPA) certified (federal or 49–state) engine cannot be used in a vehicle that was originally certified for California.

CERTIFICATION STANDARDS
Make sure the engine and emission control configuration on exhaust – controlled vehicles are certified to the year of the vehicle or newer, and to the same or a more stringent new vehicle certification standard.

CLASSIFICATION
Don't mix engine and vehicle classifications which will degrade the emissions certification standards. For example, a heavy–duty engine cannot be installed in a light–duty exhaust–controlled chassis even if they have the same displacement. Non–emissions controlled power plants such as industrial or off–road–use–only engines may not be placed in any exhaust–controlled vehicle.

COMPUTER CONTROLS
If a computer–controlled engine is installed in a non–computerized vehicle, the "CHECK ENGINE" light, the Original Equipment Manufacturer (OEM) diagnostic link, and all sensors, switches, and wiring harnesses needed to make the system fully functional must also be installed.

EMISSION CONTROL CONFIGURATION
Mixing and matching emission control system components could cause problems and is generally not allowed. Engine and emission control systems must be in an engine–chassis configuration certified by the California Air Resources Board (ARB) or U.S. Environmental Protection Agency (EPA). The engine must meet or exceed the requirements for the year and class of vehicle in which it is installed.

EMISSION WARRANTY
Voiding the vehicle manufacturer's emission warranty is not allowed.

ENGINE MODIFICATIONS
No internal or external engine modifications (cams, pistons, intakes, etc.) may be performed unless the parts are ARB–exempted or EPA–certified for use in the installed engine. Use the database on this site to search for aftermarket parts covered by ARB Executive Orders.

ORIGINAL EQUIPMENT
The installed engine and host chassis must retain all of their original emission control equipment. Diesel–to–gasoline conversions must have all gasoline engine and chassis emission control systems installed (such as fillpipe restrictor, catalytic converter and evaporative emission system).

SMOG INSPECTION
These vehicles must pass a complete smog inspection (visual, functional, and tailpipe).

Below is the California Air Resource Board's position on engine replacements in emissions controlled cars and light duty trucks.
Below is my interpretation of these guidelines. I’ve reviewed and co-authored many technical requirements in my career and I’m pretty good at it, however I offer no warrantee as to the accuracy of my interpretations. If you are planning an engine swap in California, it’s up to you to confirm or refute my interpretations. After all, this is just free information you got off the internet…
Requirement: An EPA certified drivetrain can’t be used in a California certified chassis.
Some background. There are only two emissions standards in the US, EPA and California. That was defined by the Clean Air act from the ‘70s. Several other states have adopted their own emissions “certifications” but they are certifying California emissions standards. For the 2006 GTO, all powertrains are compliant to California standards (as amazing as it sounds, a valid way to tell is to look at the emissions label under the hood). However, ‘compliance’ and ‘certification’ are different. For a 2006 GTO to be fully certified to California standards, it needs to have RPO codes NU4 and YF5. (NU4 = California emissions system installed, YF5 = California certification) Cars delivered to the other states that have adopted California standards will have RPO codes NU4 and NE1. Back in the day, there were significant differences between California and EPA vehicles. Today, the differences are small and, in many cases non-existent. An example of non-existent is the LS2 powertrain – it’s the same for all 50 states (there is only one emissions label used under the hood AND there is only one part number for the PCM). An example of a small difference can be found on ’04 GM diesel pickup trucks. The only difference is that, on California vehicles, a detected failure in the EGR system lights the check engine light, the EPA vehicles do not (The PCM part numbers and under hood labels are different).

Back to the requirement. The requirement implies that a California certified drivetrain can be installed into an EPA or California chassis. It also implies that an EPA drivetrain can be installed in an EPA chassis. In California, as a resident, it’s completely acceptable to import a USED vehicle compliant to EPA standards. The vehicle will be tested to California standards once it is registered in the state. Up until the mid ‘90s the requirements were a bit different, but it was settled by lawsuit. You can NOT import a new vehicle that is not California certified (New is defined as less than 7,500 miles on the odometer).

The interesting issue for me is how do you verify this emissions certification when the modified vehicle is taken to the referee station? The PCM carries the VIN number associated with the drivetrain. Based on the VIN, you can easily determine the make, model and drivetrain information. However, from the VIN itself, you can not determine the emissions certification. I don’t believe CA keeps a database of ALL VIN numbers shipped by the manufacturer. They can certainly tell if the donor vehicle was ever registered in the state, but many CA certified cars were never registered in CA. That leaves the drivetrain type, under hood sticker, PCM part number and RPO codes as the only method of determining the certification. The under hood sticker method is obviously questionable. There is at least one website that has access to a database of RPO codes but their database has errors and I don’t see it being good enough for the government. 

It is possible to find a valid VIN for a CA certified car that is/was registered in CA. That VIN could easily be programmed into the PCM. Problem is that if the CA system is sophisticated enough, they COULD figure out the fraud. I have no idea if this actually happens.

My donor vehicle has RPO codes NU4 and YF5, but was never registered in CA (Arizona car). The receiving chassis is a CA certified car that has always been registered in CA. I did not get a really good answer when I chatted with the referee about proving things, so this is still a bit of a risk. I’m probably overthinking it.

The balance of the document really condenses down to the following requirements:
  • The vehicle diagnostic link, check engine light and all original system components must be fully operational.
  • The vehicle must pass a complete smog test/inspection.

  • The engine and emission control configuration must be certified to the year of the vehicle or newer, and to the same or a more stringent new vehicle certification standard

You must use the entire engine and emissions control system from an EPA or CA certified donor vehicle (or, in the case of GM’s E-CARB offering, the entire package). Using an engine bottom end form one donor coupled with an engine top end from another (ie a truck 5.3L LS dressed up to look like an 6.0L LS2) is not allowed. The donor vehicle can be from any emissions class which requires more stringent emissions standards compared to the receptor chassis. It’s fine to use a donor vehicle from a different weight classification, as long as the donor vehicle has tighter standards. So that 5.3L out of a 20xx pickup truck is fine as long as you use the entire engine and emissions system. 

The engine and emissions control system is everything from the air filter through to the catalytic converters and oxygen sensors from the donor vehicle. It also includes all evaporative emissions control systems. It does not include the exhaust system after the catalytic converters nor does it include the fuel tank as long as the fuel tank is only vented into the evaporative emissions system from the donor and an unleaded fuel restrictor is present.

The engine wiring harness will need to be brought over from the donor car or a complete replacement harness will need to be procured and installed. Because of my other goals, I will be bringing over the engine and body wiring harness from the donor car. If you do not need the body wiring harness, you will end up spending a good bit of time teasing the harnesses apart. There are a few companies that sell aftermarket harnesses for this type of engine swap that they claim are compliant. For my particular swap, I would have concerns. The LS2 is throttle by wire. The harnesses I saw require a conversion to a conventional gas pedal/cable/throttle body arrangement. I don’t see that change being compliant.

I will be using the transmission out of the donor car. It’s not obvious to me that the second requirement above can be met another way. Automatic transmissions and some functions of manual transmissions are integrated into the PCM system. If you do not use the original transmission, you will need to disable the error codes that may be generated (in my specific case, the transmission module is separate from the ECM and I could remove it, but I have no idea if the ECM will generate errors because the TCM is not present). The CARB referees are well versed in how the PCM systems function and it will be obvious to them that the software must have been “tuned” to eliminate these errors. That, itself is a violation. It is possible that the referee won’t care (after all, the car will be much cleaner with the new engine), but it’s just not a conversation I want to have. Also, given how much better modern automatics and manuals are (both by design and through computer control) and how much effort would be involved in grafting an older transmission onto the new engine (bell housing bolt pattern, flex plate, torque converter, TV cable, speed reluctor), I just couldn’t be bothered.

Because aftermarket air intake systems can be CARB compliant, I’ve always thought that the entire intake was part of the emissions system. However, GM is selling their E-CARB engine package with just the MAF sensor and air filter. It’s now unclear if I can use the stock MAF sensor and air filter in a custom housing and be compliant. I need to have a follow up conversation with a CARB referee.

It’s clear that the engine can be modified with parts that have a CARB Executive Order (EO) certifying that they do not negatively impact emissions. It is important to remember that part of the EO process requires an appropriate label from the part manufacturer affixed under the hood of the car. If the donor car has modified EO compliant parts, you may have an issue with the referee unless you can produce the appropriate label. I’ve had no luck getting replacement labels from the part manufacturers.

The document implies that if your drivetrain is EPA certified, you can use EPA certified aftermarket parts. If that is true, I can see this causing issues. EPA and CA standards are different. The vehicle may well offer emissions performance much better than the EPA requirements (as is the case with my ’06 GTO). An aftermarket part may degrade the emissions performance, but if the vehicle still meets the EPA requirements, everything is fine. However, regardless of whether the vehicle is EPA or CA, it needs to pass the CA smog test. The smog test is not as stringent as the original manufacturers requirements, but it MAY be stringent enough to result in a test fail with EPA allowed aftermarket parts. To illustrate my point, all ’06 GTOs are compliant to the Ultra Low Emissions Vehicle, Series 2 (ULEVII standard). In ’06 the EPA required essentially Transitional Low Emissions (TLEV) performance. ULEVII is much more stringent than TLEV. There are no CARB EO catalytic converters available for my ’06 GTO. Magnaflow does sell EPA compliant converters for this car, these comply with TLEV standards.  So, will an ’06 GTO with TLEV compliant converters pass a ULEVII based smog test? I don't know.  Magnaflow has not certified their product for this application.  Will it pass the visual inspection which is part of the smog test? The referees are aware that Magnaflow does not offer ULEVII compliant converters and the part has Magnaflow stamped on it. If there is an issue, someone can complain all they want about how unfair life is, but they will have to replace the converters.

Copyright 2014, Leo Stearns