What is the oldest year I can still purchase & be able to pull codes? And what did one do before code readers? No "check engine light"?

You can pull codes on any year that this sub-forum is applicable to. Some systems on some years don't require a scan tool. Some do. 

And in any case "codes" are only part of troubleshooting - sometimes a big part, and sometimes they can lead the unwary down rabbit holes that go nowhere, or straight point you to a part that the computer thinks is the problem because it doesn't have enough information to tell you what the real problem actually is. 

If your skill level is only relying on codes to repair problems you are going to get into real problems and get stuck in a hurry - especially the older the vehicle. 

Short story - I wouldn't worry about it. Buy something in good shape with good history. If your goal is DIY then get educated on real troubleshooting and don't worry about the computer. The older you go back the more primitive the computer and the more likely it will be to send you down the wrong path anyway. 

GD

OBDII was federally-mandated for 1996. That's the one that is universal across all makes and models of gasoline vehicles in the US ever since, and you can buy a $15 bluetooth dongle to read codes and live data from your phone, or use a ScanGauge, or hundreds of other options.

Some Subarus (I think all 2.2s) were OBDII compatible in 1995.

 

But yea, vehicles before that still had On Board Diagnostics (OBD), and the ability to store and pull Diagnostic Trouble Codes (DTCs), and even read live data with the right reader (not universal).

 

 

All things being equal, OBDII is great. But we're talking about 25 year old cars, now. So a 1994 that's been well maintained will be a much better buy than a 1996 that's been neglected.

Like Numbchux said. Some Subaru's started using OBDII in 1995. My '95 Legacy L with a 2.2 has OBDII although I'm not sure if it has all the same sensor readings as the cars '96 and after but it is useful. I was in a similar situation and wanted to get something with OBDII. I have a scan tool that will read a lot of the older OBD protocols but OBDII is just more convenient because the tools are cheap and ubiquitous.

But I also have to agree with GD because OBDII isn't magic...it's just another protocol. If you're not good at diagnosis and you're most likely to pay a mechanic anyway then it's not really important compared to the condition of the car.

Also Trouble Codes can sometimes mean 2 things:

- There's something wrong with the engine/fuel/electrics/exhaust etc., and you may need to replace a part. Or:

- One of the sensors is playing up and giving false readings and it's the sensor itself that needs replacing.

Thank you everyone for the answers, very helpful!  The dongle & ph sound like a pretty cool way to go. I wish my old smart phone had more memory room. (one must install an app to make the diagnostics work? right?)

7 minutes ago, bork said:

Thank you everyone for the answers, very helpful!  The dongle & ph sound like a pretty cool way to go. I wish my old smart phone had more memory room. (one must install an app to make the diagnostics work? right?)

Yup. I use an app called Dash Command. I don't know exactly what it takes to run but I've used it on all kinds of android phones. It should work on most phones; but there are lots of different apps and probably some that are specifically for diagnostics Dash Command is more geared toward being a digital dash.

if the car sat unused for any length of time, rodent damaged wiring could be a possibility.

On 11/23/2021 at 9:53 PM, bork said:

What is the oldest year I can still purchase & be able to pull codes? And what did one do before code readers? No "check engine light"?

Any subaru you’re looking at can “pull codes”. 

95/96 and newer are compatible with generic OBDII scanners and connectors found in stores and eBay for cheap. 

80s and early 90s requires no tool or scanner.  Connect two connectors in the vehicle and the light on the dash flashes the code to you.

OK, I know what you mean by jumper,  & flashing dash light because I must do this on my 1995 Honda Odyssey.