another auto repair question

[Cary]

Acer wrote:
OK, I'm confused here. The Erase button on my $20 reader turns off the check engine light and deletes all codes, as in, the ODB reader says "no codes." Now, the I/M pass indicator is NOT cleared, because it will not reset itself until it runs for X time after a code erase, so there is that. But when I take it to the garage after clearing the codes (for my own troubleshooting that failed), and try to tell them "It was showing code X before", they say "No codes there, sorry, can't help you, bring it back when the light comes back on."

That does not suggest to me that the codes are protected in some sanctuary.

(We're talking several ca. 2000-2010 Toyotas.)

although

Your $20 dollar scanner can erase OBDII codes - generally, emissions/engine codes. It generally won't read or ease other modules - transmission, ABS, airbag, etc. For those and others, you need higher level (read: more expensive) scanners. There are a new class of scanners that are cheap Bluetooth OBDII dongles combined with IOS/Android apps that bridge the gap between the 2.