When in Park, my 1999 Acura 3.2TL does this thing where it accelerates and decellerates all by itself! It does not do this in drive. My check engine light is on and I am not a mechanic but I figured out that I could buy my own OBDII tool that allows me to read my own codes. Anyway, it says that I have an “Idle Control System Malfunction”. I also get a “Catalyst efficiency below threshold” code. Can you tell me what the problem is (in non-mechanic language), what needs to be done to fix it, and how much I should expect to pay a mechanic to fix it, or how I can fix it myself? Thanks so much!!
That should have been “Acura”
Idle speed is controlled via the Idle Air Control (IAC) valve. The IAC valve on your car may be dirty or faulty, or there could be a problem in its control circuit.
Now that you have a scanner, maybe the next step should be to purchase a service manual for your TL. Then you can read through the procedure for diagnosing and repairing the idle circuit. When you know what’s involved you can decide whether or not you wish to attempt your own repairs.
Catalyst efficiency below threshold can be caused by many things. A faulty O2 sensor might be the cause, but again, a service manual will take you through the diagnostics step by step.
You can get manuals at auto parts stores, book stores, or online at: