Some codes can be retrieved even after they are "cleared" depending upon the code (emissions related, anti-thief, etc.) and the type of scanner used. The "AutoZone" scanner will not pick up manufacture specific codes, as a lot of them require bi-directional capability on the scan tool. There is a reason the factory and Snap-on scanners cost between $4,500 and $9,500 dollars.....

Those prices are also the reason most techs charge so much to read the codes and diagnose your problem. They need to pay for the expensive equipment and then continue to pay to keep the software updated on a minimum of a yearly basis. The hookup and first hour diagnostic fee in this area runs around $90 to $100.

To give you an idea of what they are capable of, I can read the rpm, temp and draw of MG1 and MG2, anything at all about the engine, the battery SOC, the capacity of individual modules, battery temps and about anything else you would want to know about our hybrid systems. It is almost impossible to diagnose a problem in any modern car (much less a hybrid) without them.

With the bi-directional capability, you can perform tests on individual components or systems of the car and eliminate problem areas very quickly. The upper end units also include a lab scope for front door scanning before the info gets to the ECM.

 

Thanks for the info about some codes are retained. The light did not come back on today in the 19 miles I drove, so now not sure what to do. Guess if it was something more serious the light would have came on again today, or at least that is my rationalization.

 

Well, it's been 10 days since I turned the check engine light off and it reappeared today. There is a Toyota Dealer on my way to work so left the car with them. Here's what they found: Code P1423 ... T-SB-0364-09. Deals with the fuel filler tube and gas cap. They ordered the part to be replaced. This was probably just a money maker for them, as suspect it was probably just the gas cap and perhaps didn't get it tight enough the last time it was filled.

While there they also (didn't give me a choice) took care of the saftely recall notice 90L we all received earlier this year. They:

1. Accelerator pedal and floor surface modification.
2. Remove the sound deadening material
3. Inspect the front carpet and floor mat and clean as appropriate.

 

Tom,

That is a legit code and the fix includes replacing the filler tube. Sounds complicated but it does not take too long. The problem was the filler neck threads were not formed right and allowed some gas caps to "pop off" the threads and cause a gross vacuum leak from the tank. This is caught when the car does an integrity check of the emissions system which will set the MIL light.