I've recently moved to California and am trying to get my car registered; they require a smog check (which is possibly actually more of an inspection than the name implies?). I went by a very basic shop today (oil change, smog check, etc.) and after a good while doing all the actual testing, he tried to check on things via the diagnostic system, and ultimately came and told me that their computer couldn't talk to my computer. His speculation was that maybe since my car was newer their computer didn't know about it yet, and suggested I try a dealer. I have a 2008 Fit, not exactly brand new.

So what would really cause this? Should I be anticipating possible repair, and looking for a shop to trust, or just trying another basic inspection place (and trying to pick a more reputable one)?

Edit: I procrastinated for a while, since I cycle to work, and finally went to a test-only shop. The same thing happened, and the guy told me that some newer Hondas have high speed computers, which require the shop to buy a newer computer system. Is there any truth to that?

  • I wanted to tag this "obd" but wasn't sure about the existing obd-i vs obd-ii tags; drive-by editing welcome!
    – Cascabel
    Jun 25, 2011 at 0:08
  • a 2008 car will be OBD-II, as OBD-I hasn't been used on new cars for years.
    – Nick C
    Jun 27, 2011 at 11:55

4 Answers 4


To get smogged in California, you generally need to go to an "inspection-only" shop, that is, one that will only test your car but not fix it if it fails. (If it fails, you go to a regular mechanic and fix it, then come back for a free retest.) I believe the system was put in place to counter fraud; I don't really know how well that's working out.

In any case, the "inspection-only" shops only do one thing, and they generally have up-to-date equipment... so take it to one of them. A shop that can't read OBD codes from a 2008 Fit sounds a bit off to me. The above link, from the DMV, has a locator for smog shops.


The system might have a fuse that powers the OBDII stuff, and it might be blown. I have seen this happen on BMWs.

  • Good thought - unfortunately the fuse list in my manual doesn't appear to mention a fuse for the OBDII computer, though there are a few acronyms I don't know. I'll try and go have a look at them all later.
    – Cascabel
    Aug 9, 2011 at 2:19
  • @Jefromi Check all accessible fuses. You never know what you might find. Aug 9, 2011 at 4:00

OBDII is a connection, not a protocol per say, and it specifies a subset of diagnostic codes within ISO14229.

The transport protocols behind the OBDII connector are typically a combination of CAN/ISO15765-2 and KW2000 on Toyota and Hondas. A transport protocol does not stipulate the data that is sent/received on the bus outside of some control information. It's both an electrical characteristic and a framing protocol.

"the guy told me that some newer Hondas have high speed computers"

Not likely true. CAN operates at several speeds that auto manufacturers typically give names to them such as HSCAN (High Speed CAN), MSCAN (Medium Speed CAN) and Infotainment CAN. These different names are nothing more than just differences in how fast the CAN bus is being operated at called a BAUD rate.

HSCAN typically means 500K. The CAN standard is covered under ISO15765-2 and the max specified speed is 1Mb or 1000Kb.

So if "the guy" told you that your Honda has a high speed computer, then what he is really saying (but doesn't know it) is that his test tool either

  1. has the wrong BAUD RATE configured -- assuming test tool doesn't auto detect the BAUD rate of the CAN BUS.

  2. has an auto BAUD feature but it doesn't test the higher speeds for whatever reason like it's too old and possibly doesn't test past a certain point or that it can't. Highly unlikely considering the CAN spec has been around for several years now.

  3. test tool can read your car but the guy doesn't know how to use his test tool correctly

  4. He really has a very old test tool! I guess this is possible but then he would have a very apparent problem with all vehicles produced in the last 20 years. CAN2.0 came out in 1991 and OBDII was a US requirement since 1996 but this did not mean CAN2.0. It was 2008, when the combination of OBD-II and CAN2.0 became a US requirement. So I guess it's possible if he has a test tool more than 3 years old that has some weird partial support for CAN2.0? Unlikely.

Go to a Honda dealer and have them check it for you.


It's been a while, but from what I remember there are some strange rules that have to be followed in order to import a car into California.

Depending on when it was purchase and/or initially licenced, you may be OK - any car less that 4 years old should be OK to register in CA. If it's older than that, you'll need to get a smog check by a state-licenced facility - only they have the appropriate connections with the DMV to give you a test.

There are two types of tests - one just sniffs the exhaust gas, the more rigorous test actually puts the car on a test rig and simulates driving. Depending on where in the state you are, you may have to go through the 2nd.

But regardless, it sounds like you're wasting your time and money with the current shop. You can look up registered smog stations here: http://www.bar.ca.gov/70_SiteWideInfo/02_Tools/02_FindaStation.html

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