I just bought a blue ELM327 Mini OBD-II reader from Flebay and tried it in my '04 2.0HDi. It seems to work fine with the Android Torque app, but didn't have a chance yet to do any extensive testing as I won't be on the road till the weekend.
Just wondered if anyone else has experience with one of these, do you leave it connected all the time?
ELM327 and whatever the version 2.1 or something are ok for smart phone people. They require connection via bluetooth, they take a while to connect, some times they do weird things like stop reading in the middle of your drive but they offer a lot more via apps and an read a lot of useless data that you still don't understand and can't help you trace the problem. Like when the number on the fuel pump keeps running and you are trying to guess if its on it's way out because of missfire. You replace the fuel pump, the numbers are pretty much the same but car runs like a champ again.
Another thing is with these ELM devices, sometimes the app assholes will obsolete their own app. Let's say for instance you run Torque.v.1.8.56, everything connects first time, it reads fine, few weeks you decide to update to say Torque Pro (OBD 2 & Car) Patched v1.8.89. Suddenly it no longer read your 2003 car, may read newer stuff like Mazda CX-5..........what's the point. After a while you realize the only time you use the ELM327 is just when you check OBD2 error codes on friends cars. Now we are getting to the point I'm trying to make. Don't buy an ELM327, just get a cheap 5-10gbp reader on aliexpress/ebay with it's on screen, via cable, reads 90% of the cars and it brings and resets the codes a lot quicker.
p.s I don't leave the ELM plugged in 24/7 but I guess it shouldn't be a problem. I barely use it and I hardly look at the fancy gauges I have set. It may be more useful if you have a dashcam and you want to overlay some statistics like in the youtube videos or you need to keep track of your millage and costs. I doubt it will be bug FREE
Interesting stuff, I could well believe that some apps have upgrades that stop earlier features working. For me, the ELM cheapo was only intended for a bit of initial testing to see if the car would respond, 2003/4 was the intro year for OBDII on diesels so wasn't sure if mine would work.
Do you have an example of the on-screen / cable version that you mentioned?