How to change the cabin air filter in 1998 buick regal

SOURCE: water leak internal on buick regal gs 1998

I had this same problem. It is caused by water running downe the windshield and into the cabin air filter located under the cowling on the pasenger side. It is really easy to fix.

I've been told all "W" body GM cars have this same filter set up, so all 1997 through 2004 Buick Regals (mine is a 2001) and many other GMs have this problem. MY 2001 Regal would get 1-2 inches of water on the passenger side floorboard after a rain.

There are three things that can be done to prevent this and all three are quite easily accomplished. There is a water diverter weatherstrip above the filter that can become dislodged. Mine was out of place even though the filter had never been changed. I used RTV to glue this weather strip back in place. I also made a cover out of an old plastic 1 gallon antifreeze jug by cutting the ends off and then splitting it down the middle and doubling it to cover the filter but still remain above it so that air is not blocked. This is so that even if the diverter becomes dislodged again this still won't let water get to the filter. Once you pull the coweling, which is very easy to do with one plastic screw like fastener and two plastic "rivets" that you just pull out with needle nose plyers, you'll see what needs to be done. You'll need to use the ignition key to stop the wpers in mid-stroke on the windshield and open the hood to get clearence to the cowling. Speaking of the coweling, lastely I put a bead of RTV between the coweling and the windshield before puting it back on.
So for one tube of RTV, one old plastic jug, one hour of time using a pair of pliars and a knife I have fixed what had been a real PIA water leak. EASY!

SOURCE: cabin air filter? 2001 buick lesabre

Absolutely the light is not on because of that its on from something else/has something to do with the engine/Please rate my response thank you very much

SOURCE: locked radio 1998 buick regal

You will need the radio code. The dealer will have to provide this information unless it is written in your owners manual.

SOURCE: 2003 Buick Regal Service Engine Soon light.

The error that I'm showing for error code P1133 is 
P1133 Heated Oxygen Sensor (HO2S) insufficient switching bank 1 sensor 1(Rear Bank).  I would suggest having both of your Oxygen Sensors replaced if you haven't already had that done.  Hope this helps.  Thanks for an honest rating and for using FixYa.

SOURCE: Have a leak under passenger side dash when it rains. I think the door under the cabin air filter isnt closing is it an easy fix

Having just repaired this problem in a 1998 Buick Regal, I can tell you that fixing the water leak is actually quite easy. It took me quite a while to track down the source of water, but I have discovered that it comes through the cabin air filter. There is a seal on the passenger side of the cowl (A two piece unit, black plastic, against the windshield) that seals it to the windshield to prevent water infiltration. It is very small and somewhat hard to miss. I took the cowl off to change the filter when I discovered this.

You can make a diverter to go over the air filter under the cowl, or even easier is to use some clear RTV silicone (avalible at any automotive and most hardware stores) and put a good bead on the old seal. When you re-install the plastic cowl, be carefull where it goes against the windshield to make sure you don't "smear" the silicone. After you re-install the plastic retainer hardware, smooth out the bead and clean up the excess silicone(a wet finger and some old cardboard works great). Let it dry and clean up the water in the passenger compartment.

Cleaning up the water is the hard part. Removing the plastic trim around the door (if you grasp the trip peices firmly they just pull up off some metal clips,but they can be quite stubborn) you will notice the carpet just pulls up. At the bottom front corner of the front doors the carpet has a plastic hook that is around one of the trim clips. Lift it off that and the rest of the carpet towards the firewall just pulls up. If it has been a long problem, your carpet may be moldy. Also, the carpet edges and some of the more hidden panel clips are very sharp and may cut you while you are poking around, so be carefull.

Since the water entered through the air filter and right over the fan, you will at minimum want to replace the filter. I had mold and moss growing on mine. My fan also squeels and chirps now, so I know it got wet. Not much to do about that but replace it or carefully lubricate the motor.

In your question you mentioned a door underneath the filter not closing. On my '98 Buick Regal there is no door or valve of any sort. The filter sits right above the fan blades. It is the cowel's job to prevent water from entering this part of the vehicle. I hope this helps you fix your problem.