Hi, Recently I had Agency Power headers (without pre-cats, but do have air rails) installed. Not sure if the shop disconnected the battery. Today received both CEL's: P0421 & P0431"Warm up catalyst efficiency below threshold" in both banks. From what I gather it could be a mis-spaced O2 sensor (this is Greek to me, apologies for my ignorance). However, I've also seen folks who have turned the battery off for a while to allow the car to "relearn" the new setup. Can someone please let me know: (1) How long does the battery have to be off? (2) What is the process when turning it back on? (3) Does it screw up the alarm? (I don't care about radio presets, etc) (4) Any other tips? Thank you as always!
The switch is in the front trunk or boot, when you open the hood it is a turn switch front left. It may be a little tight, but if I remember right, turn it to the left, there is a diagram on it. Wait for 1 hour, then turn it back on. You will have to input your radio code, and you lose all your presets and settings on your radio if it's a factory Becker unit. When you restart the car it will run a little rough, until it learns a bit, then the idle will smooth out. If the Cel is still on, might want to take it back to your shop.
If you don't have the code you could have any stereo shop use the little keys to pull it out and read the serial number on the back. Then you would need to call your dealer and have them get the code from Becker, takes a couple days.
Make sure that you leave your front hood open and your driver's side window down a bit before disconnecting the battery. While you can manually open the front trunk with the pull cord under the left dash, it is difficult to open the driver's door with the window fully up. The window won't drop down when you partially lift the handle because the power windows have no power.
Thank you, thought of both - front lid left partially open and window down. Also, I have the radio code, so I am hoping all will be well in the morning
One more thing. When you restart the car in the morning after having the battery off, you need to let the car idle for 10 or so minutes before driving it. I had read that this allows the ECU's to "relearn" for proper driving settings. I seem to remember that once you hear the radiator fans start to cycle then it is ready. This is usually about 10 minutes of idle from a cold start.
Many thanks again, and I know to wait with the key in position "II" for 10+ seconds before turning the car over as well.
Turned the battery back on this morning after being off for 12 or so hours. Waited 15+ seconds with key in "Position II", heard the expected "clicking" of the computer relearning whatever it has to relearn. Turned her over, started rough with little RPM, but only for a few seconds, then normalized down to say 1,100 RPM. Idled for say 5 minutes in the driveway, then went for 10 minute short run. No "SLOW DOWN" light (which has been a problem forever) and no CEL. Maybe beginners luck or the battery reset actually did some good, who knows, but so far, so good. I guess only time will tell. Thank you for your help!
Ha, I knew it would work. Another little trick, say you didn't tighten your gas cap all the way after a fill up, go for 3 20 minutes drives over 3 days, CEL light goes away, granted of course you tighten the cap.
