I have a 2001 Highlander AWD, V6, with 100M+ miles on it. Over the course of the vehicle’s life the check engine has come on and then either goes off by itself (after a few weeks) or my mechanic will reset the system and light will stay off for months or even a year or more.
Recently the light went on and when the mechanic tested the codes it was a jumble of codes related to the fuel/tank system (most of the codes in the past have been similar).
Questions: Has Toyota issued any sort of software upgrade to the computer to make it less sensitive to noise in the system?
Does Toyota have a position on the check engine light in the 2001 V6 engines? How would I find out? I checked with dealer and got a brush off.
Any had this problem fixed? Really fixed? If so, what as required (I realize that there are insufficient details).
Most of the jumble of codes dealing with the fuel tank are evap system codes, like ‘P0442 - Evaporative Emission Control System Leak Detected (small leak)’. On an 8 year old car with 100K miles (At least I hope that was a typo), vacuum line leaks are not uncommon. There is no ‘software’ update to fix this. The leaks must be found and fixed to turn the light back off. The dealer knows this truck is no longer under warranty, and will do nothing for free.
However, unless a charcoal canister, purge valve, sensor or other major device is damaged, most evap codes can be fixed with a few bucks worth of vacuum line.
So, your mechanic goes to the repair manual, an online manual, something like alldata.com, or somesuch source of information, and gets the vacuum hose and line schematic for the EVAP system.
S/He then, uses the Diagnostic Trouble Codes (DTCs) to find out what EVAP circuits have detected problems. S/He, then, uses the technical data to test/inspect/repair those things which set off the DTCs…or, you get a mechanic who understands these procedures…AND, carries them out.
You could have had problems which were marginal, all these years. Now, they’ve gotten worse. It’s unlikely that they will heal themselves.
Some auto part stores will check the codes for free and tell you what they are. They should be in the format [P0123] If you post the results back here we may be able to give more specific advice.
Pay attention to what Hellokit wrote.