Scan Guage Accuracy

I'm considering purchasing a scan gauge and would like to know from those of you who have them if you find them to be accurate?  My main purpose if for transmission temps but I would guess if it tends to be accurate say in MPG I can assume its fairly accurate across the board?

I can't give you a precise answer to your question but when I compare calculated mpg vs gauge mpg I think I am usually within 0.5 mpg.  The gauge mpg reading is typically a little higher than calculated.  I attribute that in part to the fact the speedometer reading is about 2 mph higher than gps speed.  I believe the gps reading to be more accurate.

I bought the ScanGauge primarily to keep track of transmission temp to extend its life.  Usual temp on near flat roads run about 201.  While pulling long steep grades it increases to about 207.  Once on a steep mountain pass in Colorado it climbed to 209 and I decreased my speed and the temp quickly dropped back to about 207.  I have noticed using engine braking while descending a steep grade the temp increases in a similar manner.  Are these temperature readings accurate I have no way of saying for sure but knowing relative changes has its benefit.

I typically have my gauge set to display transmission temp,  instantaneous mpg, average mpg, and either coolant temp or intake air temp to give me an idea of outside ambient temp.

I frequently glance at the gauge so I would say it was a worthwhile purchase but I am a bit of a geek when it comes to looking at performance data.

So I'd estimate at those temps your transmission would need to be flushed around 40,000-45000 miles.  I can see the benefit of having the gauge then. Thanks


I'm having my transmission flushed next week at 30,000 miles. Be a good time to start monitoring temps from then on.

Hi Joseph,

I've had a Scanguage for 3 or 4 years now.  I can't say how accurate it is for I really don't know.  I use it primarily as a real-time guide to smarter driving for best fuel economy.  I like to display the throttle position (I think labelled TPS for Throttle Position Sensor) to tell me how close to the floor I have the gas pedal because sometimes I don't realize how much gas I am giving.  That along with instant gas mileage, speed, and average fuel economy.

Too bad the average fuel economy on mine resets with every ignition off/on cycle.

Sorry I can't provide useful information to your question.  I figure I'd share how I utilize mine.

Ron Dittmer

Adding: I mounted my Scanguage on top of my backup monitor of which I re-mounted in place of the rear-view mirror.  The ODB cable is behind the headliner and door pillar, out of sight all the way to the connector below.

Thanks Ron, what I am learning is those of you that have them do find them useful. They don't exactly give them away so its good to know people do find value.

I have been thinking of getting an ODBC reader but researched it and found both Scangauge II and Ultragauge to both get good reviews.  And then got buyers lock and could not decide which one so I got neither.  Anyone who has used both and can comment?

Jatrax.. I looked at them briefly as well.  I like their display over the scan gauge however I've read where several felt the unit wasn't as well built. They are much cheaper and supposedly give the same info. I don't so much care about the cost difference as I do to only buy it once. 

Agree with the buy it once.  But I do like the Ultragauge screen better.  Just checked the Ultragauge website and they say they are sold out until end of June??  How can that be?  Sounds more like they are in financial trouble.

jatrax, oooooor people are reading our posts and made a run on them.!  I guess that pretty much makes up my mind which one to choose.

I got a Memorial Day weekend sale email from Advance Auto showing a 25% discount for a ScanGauge II ($120 sale price). 

https://shop.advanceautoparts.com/home?c3apidt=20574465980&gclid=CPWy97eukdQCFVg8gQodmVILwA&gclsrc=aw.ds

I didn't compare prices elsewhere so can't comment if this is a good price or not.  I bought my ScanGauge last year from Advance that was offering a pretty good discount at the time.

Just wanted to mention this in case someone is looking to buy one.

fandj... Thank You, I ordered one; 112.00 is a good deal from what I could find.