Shampue

Kind of a stupid question maybe, but hey...

I was watching Two Guys Garage the other day and they had a Corvette (I think a 02)

They hooked up a device to the OBD port which showed them current AND past error codes the car had.

I, obviously do not have access to one of these handy dandy devices so I stopped by Autozone and asked them to hook theirs up. I recently bought my car and was just curious about past engine codes.

It came up with no codes and the employee said the device would only display current error codes, and my SES light would be on if I had any current errors..

So, how did the Corvette show past codes? Is this a GM thing or is this just a limitation with Autozones device? How dumb am I for even posting this?

I was just hoping to get a glimpse of past errors because I was curious about the OS sensors and the Idle Control Valve, I think they may need replacing. I also wanted to know if any of the cylinders had a history of mis-firing

thx

capri debris

Even basic code readers will show current and past codes... sounds like the Autozone guy was "tarded". The only reason I can think of that no past codes could be read is because there either weren't any to be read... or they have been cleared by the last pesron who scanned the car.

petrock

The AutoZone guy wasn't 'doing it wrong'. The codes had probably been cleared by the last person to scan the car, or when you last disconnected your battery for more then a minute or two. Past codes are codes that triggered the CEL and went away before you cleared them. Unless they are cleared, CEL codes remain in memory even if the problem causing the CEL has been fixed and the CEL has turned off. For example, say you disconnect an O2 sensor and go drive the car around a bit. The CEL will turn on. You them plug the O2 sensor back in and drive the car around a bit. The CEL will turn off, but the original code that triggered the CEL in the first place will still be in memory. A scan tool will still find that code. If you then clear the code, or disconnect the batter for a minute or two, the scanner won't be able to read the code anymore.

Hope that cleared things up...

Shampue

Good to know, thanks fellas