My check engine light is on but no codes
Many car makers design their computers to alert the driver of a problem by turning on the check engine light and storing a trouble code in the computer’s memory. If a problem occurs but does not meet the software’s threshold for the number of times the problem must occur before lighting the check engine light, the trouble code may be stored as a PENDING CODE. In that case, you could scan the computer and find a code, even though the light wasn’t on.
There are other cases where there’s no check engine light but codes. For example, any problem that affects the emissions system will automatically light the check engine light. But if the problem is not emissions related, and also not critical, it may be stored in the computer but not light the check engine light.
Some computers are programmed to see a problem, store a code, and light the check engine light. Then later, if the problem does not reoccur, the computer will turn off the check engine light and store the code as a HISTORY CODE.
© 2012 Rick MuscoplatPosted on by Rick Muscoplat