I've been trying to get the girlfriends car ready for the emission
check and would like to look at the engine live data. There appear to be
a number of PC interfaces for the ODB connection. Here is one:
Has anyone used any of these and any recommendation. On the frugal end
of the price scale would be preferable.
I've been using it long time. I use free shareware and laptop thru USB
hook up. I assembled interface in a small metal enclosure using a kit.
All my family car is Japanese so the coneector is ISO spec. Domestic
ones may have different connector.
I haven't used them so don't have a recommendation on which would fit
I don't know how your state checks emissions, but here in Illinois
they don't even put a sensor in the exhaust anymore for the later
ODBII cars. '96 and later I think. Just use their ODBII scanner.
The key to a scanner here is that it can clear codes.
You don't want to go to emissions testing with a stored intermittent
Just did the test here last month and had my son check it with his
scanner a couple days before I went.
He cleared an intermittent EGR code.
That would have flunked me I think.
We have an older ODBII reader that would only read the code, but he's
got one that can clear them.
It's a "pricey" Snap-On, but he's a mech.
I'd talk to some pro mechs before I'd put any heavy money into
There's a lot of stuff on the "net" too.
There are also real "gotchas" with some older model ODBII cars
regarding the interfaces.
But I think the newer cars are pretty consistent.
The value of robust OBD II software is the ability to tweak the engine
parameters by going into ECU if one knows whats/he wants to do. Also you
can monitor engine performance real time. My son used to play with it
quite a bit when he was a high school kid. After realizing he squeezed
every drop out of his car he quit doing it. The car is Subaru WRX STi.
On Wed, 23 Feb 2011 17:53:32 -0500, email@example.com wrote:
I used a paper clip to read ODBI codes. Flash sequence on dash light.
Don't know if you can reset trouble codes with a paper clip on ODBII,
and don't even want to know.
I'll use a scanner for that, thanks.
Since I do my own repairs I need the scanner anyway.
As far as disconnecting the battery, you can fail emissions on
"readiness" if the ECU hasn't done its test cycles after a battery
That can take many hundreds of miles of driving.
But supposedly the same "readiness" states are reset to zero when you
clear a code with a scanner.
Different cars get back to "readiness" differently too.
Anyway, scanners are cheap and can save you lots of money.
I don't want to disconnect my battery and lose my radio presets.
Agree. I doubt you can reset codes with a paper clip on ODBII, which
what cars have been using for many years now.
That's right. It's not as simple as just clearing codes before going
for an auto inspection. You can clear them, but the test facilities
rely on OBDII require that the flags for the items requiring
be set. And that takes a certain amount of driving and or time.
in NJ they will pass late model cars with all but one of these set.
cars can have two that are not set and still pass. If the check
light is on, you always fail.
The flag that take the longest to set is the fuel system evaporation
I don't know why, as all it would seem to measure is if the tank
will hold a small pressure. But, for whatever reason, it takes a
to set and it;s not even clear what exactly sets it, ie driving, type
engine starts/stops, amount of fuel in tank, etc. I've gone through
here in NJ with that one not set a couple times after fixing something
I guess I'd evaluate how much a hand held scanner costs versus one
that is an interface to a PC and what the feature tradeoffs are. I
expect on the PC type you can see more info and actually change some
parameters. But for most auto repair all you need is the code that
any of the hand-held type will give you. Then if you need further
usually googling with that code and the vehicle model will give more
On Thu, 24 Feb 2011 06:39:21 -0800 (PST), " firstname.lastname@example.org"
The more information the better - unless you don't need it or it
So far all I've needed is the code. Got right to the problem.
I'm sure there are tricky problems where somebody can make use of this
software, just never ran across a use for it myself.
Simple OBDII code diagnostics are pretty good IME.
They put a lot of work into OBDII
But I only drive simple Chevys and Pontiacs, and maybe am lucky.
Most sophisticated testing I ever did was put my old VOM on the
injectors in my pre-OBD '88 Celebrity 2.8 when a mech told me the
rough running was one or more injectors.
They were all within spec so I bought 6 new ones.
Expensive, since the damn things were about 70 bucks each.
But it purred like a kitten ever after.
Maybe this software could have pinned it on just one or two of the
But they didn't have this software then.
I may end up buying it yet, though I haven't had a bad injector since.
First I need a laptop. But my kid has plenty of spare desktops, and I
have 2 unused CRTs, so that might do.
I hate laptops anyway.
On 2/24/2011 3:16 PM, email@example.com wrote:
You get real time data, and you can log it. In my case, I'm throwing a
P1131 which could be caused by a dizzying array of things.
Knowing when and what the lean fault conditions were would be a big
help. Excatly what was the engine doing when it set the code; the code
has no specifics behind it.
Yeah, I guess it could give you more insight into what could be wrong
might help identify the cause. In some cases the code is all you
in "left bank oxygen sensor heater circuit". But in other cases,
lean fault, the code doens't point it to a specific component that is
If you get one, I'd be interested in finding out how well it works for
The price of $139, less 30% off sounds reasonable. I looked at them
a while back and wound up going with the more basic handheld one.
Back then, the PC type cost significantly more. It's been OK for
things, but the additional info you get with a PC one, might indeed be
well worth the added cost.
That's a heated O2 sensor code. I see with Fords it can be set by MAF
and injector issues, and others.
Good place to use what you want to use.
OTOH, it might just be the sensor. I didn't look into that to
calculate the odds.
Problem is these sensors can be pricey so you don't want to throw
parts at it.
Sounds like you're doing the right thing. Getting some new gear too.
Watch your prices on sensors if you need one.
Last year my daughter's Mitsu threw codes for all 4 O2 sensors.
It was a pain figuring out the "bank" and fore and aft because there
were about 5 different codes. But I determined that all 4 were
tossing a code.
Then I just had to make sure the cat wasn't bad, and would destroy 4
new sensors after I put them in.
That's why I now own a remote temp reader!
Anyway my son picked up the sensors at our local Murrays.
You want OEM usually.
Murrays usually prices competitively and I don't do much price
But since 2 of the sensors were a bill each I went online.
Took them back to Murrays unopened.
Think I saved about $130 by getting them on Amazon.
That would assume it even has an output voltage or that you knew what
the output voltage was supposed to be under whatever the condition
was when you measured it.
In the case of the example I gave "left bank oxygen sensor heater",
about the most clear example of a specific fault that usually doesn't
need any further investigation before replacing the sensor. The
is not about what the sensor is measuring. The O2 sensor has a
heater in it to warm it up so that it's operational from the time the
engine first starts up from cold. That code means the heater
circuit does not have the correct resistance, ie it's open or shorted.
It could be a connection/wiring issue, but usually it's the sensor
itself that has failed. O2 sensors going bad is one of the most
You could measure the resistance of the O2 heater after disconnecting
it, assuming again you knew what the correct value is. Kind of comes
down to how much checking and research you want to do before replacing
a $60 part. Also, no need to check all of them. The car could have
them, but the error code is specific as to which one is faulting.
Can't you go into ECU memory at specific location and read the stored
data in Hex usually? You can even fiddle with the value if you want to.
You can even dump the cmemory in print form and read the machine code.
(low level language) You are right, O2 sensors give lots trouble. So far
I replaced them three times on different cars. One knock sensor, one
ignition wire. My interest is in things like fuel-air mix. ratio,
acceleration rate, relation between gear shift-rpm-speed, etc. Also
calculated estimated Hp torque, things like that. Today's cars are more
electronics than mechanics. What do you think hot rodders are doing
O2 sensors are usually no fun to replace, but I did the upstream on the
the bank indicated and cleaned the hell out of the MAF. Threw the code
again after driving for a while. I'm not unconvinced it's not a DPFE or
If I see when it it leans out, I should be able to rule out injectors or
vacuum leaks. At least I think so... The code does not tell me enough.
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