Subaru Engine Swaps and the California BAR/State Referee Process

Subaru Engine Swaps and the California BAR/State Referee Process

Dec 15, '22

In this post, we'll talk about the engine change guidelines for the state of California and the BAR engine change referee process. We'll include the critical information you'll need to know if you are looking into this process when swapping your Subaru. This is not a specific guide for any particular swap but a guideline so you know what needs to be done and what to expect.

We use the terms "BAR" and "Referee" interchangeably for the information below.

Cliff Notes

  • Your engine must be the same year or newer than your chassis
  • It must have all of the emissions components that match the new engine
  • ECU must not be modified and have a matching Calibration ID
  • All parts on the engine must be OEM or have a CARB EO Sticker

Preface About the BAR Referee Process

I want to start by saying that California recommends people not changing their engines. From their documentation, "Engine changes can present problems and challenges to vehicle owners, inspectors, and technicians. Our recommendation is to rebuild and reinstall the original engine, transmission, and emission control system configuration, use a California-certified engine, or use a CARB exempted engine package." 

For the complete guidelines, you can click here.

That said, we disagree with this because we can put in newer engines that meet the modern emissions standards set forth to keep older cars on the road longer and run cleaner than when they were initially manufactured.

General advice is to have a well put together car and engine bay. Ensure things are secured as the factory intended, and the car is clean. Take a little time to make sure everything is washed inside and out. Don't give them an excuse to say your car is a "hooptie" and start looking for reasons to fail you.


What Mechanical Components Do I Need to Change?


The engine must be the same year or newer. There are notes of "engine classification," but this would not apply to the Subaru-to-Subaru swaps because these are all passenger vehicles. When swapping the engine, use all of the OEM components if possible. Parts like silicone hoses (without CARB EOs) will cause you to fail automatically.

Retaining OEM parts do not apply to non-emissions components like AC, power steering, and the cooling system. You can run an aftermarket radiator and power steering setup without issue.


BAR requires all associated components to be hooked up if using an OEM intake. Yes, this does include the intake duct from the headlight to the snorkel box in the fender, which likely will not fit. The simplest solution for most swaps (yes, it's as weird as it sounds) is to run an aftermarket intake designed for the new engine with a CARB EO. These intakes have been approved with the duct and snorkel box removal.


The stock exhaust with catalytic converters must be installed per OEM specifications. For 2002-2005 WRX and 2004-2005 Forester XT engine swaps, this also includes the catted uppipe with EGT. The catback can be whatever you choose.

Fuel Tank

Although the fuel tank is not specified as a required part to be changed, you will most likely need to swap it out to get the correct emissions components and the matching evap equipment in the car's rear. The most common situation is a 2002 or older vehicle getting a newer engine. In this case, an extra valve must be added in, and the best way to do this is to swap the fuel tank along with the evap components. More about this can be found by clicking here.

Secondary Air Injection

If the new engine is equipped with the Secondary Air Injection System, it will need to be added. We build a custom fuse block for these applications as part of the harness merge.


The ECU needs to be wired up correctly (please click here for our services) and have a map (also known as a calibration) that matches the factory Subaru ECU for your new engine. The ECU also needs to have all readiness monitors passed. Most basic scan tools can check that the readiness monitors are set. Typical monitors are EVAP, O2, Catalyst, etc.

The video below is a good resource on readiness monitors and the drive cycles required to set them. One quick tip is to have a little over half of a tank when trying to set these. They will not be set if the fuel level is too high or too low. We also found that driving as long as you can at 65 MPH without changing speed pretty quickly sets most of the monitors.

Cobb Accessport

Yes, you can pass with a Cobb Accessport Stage 1 tune! Cobb's staged tunes have CARB EOs, so you can pass with a Cobb AP tune. Make sure the Cobb AP is unplugged at the time of the inspection, so the Referee has access to your OBD2 port. Also, bring your EO sticker with you since the Referee will check that you have it in your car. 


How Does the Process with the BAR Referee Work?

Phone Interview - The BAR number is 1-800-622-7733

When you have everything in order, the first step is to call and schedule a phone interview. During this phone interview, they will go over your swap and the critical pieces of information you need to know. This is an excellent opportunity to ask any questions about the process. When you get through with the phone interview, they will request pictures to send via email to the basic checks before you come in. The upside here is that if there is something obviously wrong, they likely will catch it here before you drive it down. As we've found out the hard way, this first set of checks is not a guarantee but likely should help you pass on the first try.

ECU Calibration ID (CAL ID) - Calibration Verification Number (CVN) - VIN

You'll need to get a verified ECU calibration ID. The calibration ID is the mathematical equation you get when you add up all the information on the ECU. This is a unique identifier of the information on your ECU. If a value is changed, the calibration ID will too, which is how they can tell if the ECU has been modified. If you have access to a tool that can read this information, you can get a screenshot of it or take it to a Subaru dealership and have them read it. The dealership will call the Subaru Tech Line and confirm the ID matches an OEM ID and print out a report for you to give to the referee.

They will also include a Calibration Verification Number or CVN that should be included in the paperwork.

You'll also get the VIN that matches the car that the new ECU came out of. This is so they can confirm where the ECU came from, and when you going through a smog check in the future, they can match the VIN on your ECU to your vehicle even though they will be different.

Cobb Accessport

If you have a Cobb Accessport, the process will be the same as above, except that the CAL ID will not match an OEM Subaru. Instead, it will match one of the CAL IDs listed with the Cobb CARB EOs for the ECU you are using. The list can be found by clicking here. Take a picture of the applicable CARB EO and include it in your documentation. They will verify this before you come to the in-person appointment.

Readiness Monitors

Subaru should also include a list of all of the readiness monitors that we discussed above. Once again, if you have a scan tool that can read this information, you can take a picture of that screen that shows that they are all passed.

Engine Bay Pictures

BAR requires an OEM (or similar, I assume) hood bolted to the car as the factory intended. So take a couple of shots of the engine bay as a whole so they can see each section of the engine bay clearly.

Exhaust Pictures

Make sure to get some clear pictures of the exhaust so they can see that it is OEM and installed correctly. We suggest making sure to include the header, uppipe, and downpipe.

Aftermarket Parts

If you have any aftermarket parts, make sure you have affixed to them the CARB EO sticker from the manufacturer. This includes the Cobb Accessport tune if you go that route. You can place the sticker for the Accessport CARB EO in the engine bay.

NOTE: Take good pictures of the parts they request and follow directions! Put the pictures into a PDF and include your name, license plate, and VIN in the file name to make sure they can identify you. When you send the email, they request your name, VIN, and attention to the person you have the phone interview with. This process can be tedious but be patient and follow instructions. 

I Sent in my Paperwork, and I've Set Up an In-Person Appointment

Excellent! This is a big step, and hopefully, you can pass on the first try. Remember to make sure your car is clean inside and out. No one likes to dig around in a dirty car! Show up early, so they are not waiting on you. Failure to arrive on time can mean your appointment will be canceled and pushed out for rescheduling.

Expect this process can take up to 2 hours. They will be inspecting everything from front to back, and this takes time.

If you get your sticker, they may try to stick it in the engine bay. We suggest the door jamb, as noted in BAR's guidelines. This will help keep it safe from degradation over time.

In Case You Don't Pass
Hopefully, you pass on the first try, but if you don't, they should give a hand out with information about why you didn't pass. Do not try to argue with the tech or try to plead your case at the inspection. It will not work and will cause you more problems. Listen to their recommendations, and fix them. 

If there is something you disagree with or their documentation has issues, you can ask them what information you need to submit to BAR to show that you have it set up correctly. There is also the number of the regional manager on the paperwork they give you. We recommend contacting them as well for any questions you have about why you did not pass. 

One case, in particular, was that their documentation did not distinguish between the 2004-2005 STi and 2004-2005 Forester XT since both are "2.5 Turbo Models". The problem is that the STi does not have a catalytic converter in the uppipe, while the Forester XT does. The customer needed to submit the Subaru documentation that showed the STi did not have the catalytic converter, and they passed the after the fact. 

In Conclusion

We know this sounds like a tedious process and there are many ways you can fail. However, we at iWire highly recommend making your car legal with the state. It will save you from a lot of headaches and hassles down the road. The spirit of BAR is to have cleaner air after installing the engine, and the more we as a car culture can show them we're trying to do the right thing, the more likely we are to get to keep enjoying this hobby!