My CEL went back on yesterday afternoon, 345 miles after having reset it, and about 100 miles after passing inspection. Here in NJ, we only need to get inspected every 2 years.
I’ll probably look into it some more, as it’s worth having things operating properly, especially as in modern cars the components are interrelated - the computer adjusts things based on signals that it’s getting. But I can do this at my leisure.
What’s your take on these connectors that hook up the car to a laptop and read all sorts of other measurements (coolant temperature, O2 sensor data etc.) in addition to the code? I can see why a mechanic who does a lot of these doesn’t want to be bothered dragging laptops around the shop, but ISTM that these are a better deal for the casual DIYer.
But of course, that’s only if they work. I myself bought one of these ELM327 clones off eBay for under $20 earlier this week (it hasn’t come yet, as it’s being shipped from China so I can’t tell what it does).
I never really worked on cars in any serious way into the OBD-II era, so perhaps things are different now, but my impression is that they’re not significantly more useful for diagnostics than a regular code reader. Since car makers try pretty hard to make it so any odd sensor ranges that would cause problems will trigger a trouble code, problems that are diagnosable with raw sensor readings but which won’t trigger a trouble code are fairly rare.
They are pretty interesting and for a DIY-er or general car enthusiast they’re probably valuable as an education tool, so for instance if you know what the normal behavior of a sensor is, you might be more able to comprehend the implications of a trouble code saying that sensor is out of range. If the $20 one works, it’s probably worth that just for the neat-o factor!
I have one and it works well. You do get some more stuff compared to the simple readers. For instance, I can watch sensor readings in real-time. If I suspect a coolant temp sensor that is not setting a code (yet), I can start the car and watch the sensor readings as it warms up.
I can also watch the block learn at different rpms which tells me there is probably a small vacuum leak (again, not enough to set a code, but is still causing rough running).
It has other features I haven’t used yet, like it can make a graph of the O2 sensor voltage transitions which apparently will tell you that a O2 sensor is getting weak although it hasn’t failed yet.
I also like that it works on just about any car, it does a bunch of different protocols. The cheapos often only work on a few brands.