I have a 2003 Civic that has recently (past two days) been making rattling noises when the car is stopped. If I hit the breaks, no noise, but if I'm stopped at a light it'll get increasingly louder. I've check all my fluids and my air filter, and everything is in good shape. I don't need to take my car in for an oil or oil filter change for another 1000mi. What could it be?
What does a rattling noise mean?
This could be the problem. There are aluminum covers around the exhaust pipes. This keeps heat from damaging electrical wires and electronics, these could be loose and just need tightening. Try that before u look at anything else.
What does a rattling noise mean?
Heat shield on the muffler, get under there when it is cold and shake the exhaust near the muffler.
The answers above are a more likely reason for the rattle than one I thought of. But I wondered why applying the brake stops the rattle? One common reason would be a brake related vacuum leak which is alleviated by pressing the brake pedal. A vacuum leak causes a rough idle, and the rattle is simply a symptom of a rough idle when the engine starts shaking your exhaust system and heat shields as diagnosed in the answers above. Another reason applying the brake would stop a rough idle is when you have a sticking or failing Torque Converter Clutch (TCC) solenoid in the transmission. The TCC solenoid should be disengaged at idle, but can hang up and partially engage causing an engine to stall or idle rough. However, the TCC is automatically disengaged by applying the brakes at any time (idle or at road speed). So I'm guessing that you may have a bad TCC solenoid in your transmission. The transmission TCC problem could be covered under your power train warranty or a secret warranty because Honda knows they have a TCC failure pattern (see TSB bulletin below). Tell the Honda shop technician that your engine idles rough until you apply the brakes.
probably a loose heat shield on your exhaust system
