A neat thing about wordpress is that I can see search words used to find this site. One of the most common themes boils down to “how do I clear OBD-II error codes that set off the check engine light (CEL)”. So I figure I should make a formal post about how to clear those errors on the SAAB 9-5.
There are two easy ways to turn off the amber check engine and ! lights on the 9-5. Neither of these techniques will fix whatever caused the code in the first place. You will want to check out the codes in the “on board diagnostics” (OBD-II) and fix anything that is causing you trouble.
The quick and dirty way is to pull fuse 17 out of the fuse box, drink a glass of iced tea, and then put the fuse back. This will reset the engine management system and cause the CEL to go off. That’s it. The fuse box is behind a panel at the end of the dash on the driver’s side. The back of the panel has a diagram of which fuse is which.
The way I clear the codes is with my OBD-II code scanner. I made a post about it and the details of what it does are there. It will read the codes and then you can erase them, turning off the CEL in the process.
When the check engine lights come on the car might also go into “limp mode” where it starts in 2nd gear and doesn’t shift into 4th. This is really annoying when you know the reason for the check engine light isn’t really that important and/or you have people in the car with you.
“There are indeed different limp home modes associated with various components. The throttle body limp home mode is activated when there are problems in the throttle control (like bad throttle position sensor signals and so on). The ECU fires the limp home solenoid, which locks the butterfly to the accelerator cable and cuts the power on the throttle motor. After this, the drive by wire is gone, and you control the throttle directly with your right foot. It also continues to fire the solenoid every time you start the car if the condition and the codes are still present. So the only way to clear it is to kill the codes and unhook the arm on the throttle body (a pair of needle-nose pliers gets the job done).”
The way I get out of limp mode (ETA: when it doesn’t fire the limp home solenoid) is by putting the car in park, turning the car off and removing the key. I then put the key back and start the car again. The amber engine and ! lights will still be on but the car will operate in normal mode.
Keep in mind that the car goes into limp mode to protect itself, so you shouldn’t take it lightly.
There is also a red triangle check engine light. I don’t have much to say about it because, knock on wood, I have never had to deal with it. It is the serious check engine light. The red triangle means “pull over right now and call a tow truck”.
There is a video on youtube that does an excellent job of explaining how to get the throttle body reset.
Basically the amber engine light is like a child saying “I need to go to the restroom” and the red triangle is like the same kid saying “never mind the restroom, I need some clean pants”.
When talking about the limp home mode, don’t forget about the limp home solenoid on the throttle body. You can’t reset this to normal without a bit of mechanical intervention.
@dplatonoff
This is good to know, I didn’t realize that it wouldn’t reset itself. Would you object if I cite your comment in the main post in case people don’t take time to read the comments?
I guess I’ve been luckily, so far my car has only gone into limp mode for a couple of minor problems (a bad upper 02 sensor and the darn gear selector position sensor). They must have not affected the solenoid. Could this mean there are different levels of “limp”? If this is the case, I wonder what the traits of each level would be… and what errors cause which limp. Interesting.
There are indeed different limp home modes associated with various components. The throttle body limp home mode is activated when there are problems in the throttle control (like bad throttle position sensor signals and so on). The ECU fires the limp home solenoid, which locks the butterfly to the accelerator cable and cuts the power on the throttle motor. After this, the drive by wire is gone, and you control the throttle directly with your right foot. It also continues to fire the solenoid every time you start the car if the condition and the codes are still present. So the only way to clear it is to kill the codes and unhook the arm on the throttle body (a pair of needle-nose pliers gets the job done).
@ dip
Excellent explanation of the limp system. I hope I never have to experience this throttle body type of limp mode!
Do you mind if I cite your comment in the main post to make sure everyone sees it?
The WIS has a pretty good explanation of how it all works, naturally.
And of course you can quote this stuff in the article - the comments are out there for everyone to see anyway, so it would be silly to try to prevent you from using them ;]