brake light replacement - what am I doing wrong

This is for a 2008 Cayman (base) with ~94k miles on it. Right brake light warning came on. So far I have tried 3 times with replacing the bulb and the warning does not go out. Also while the brake light works, when I turn on the headlights , that side comes up as braking all the time and not as a normal taillight until the brake is pressed. I tried an Osram/Sylvannia 7225 (what I think should be right). Also a 7528 and a phillips 12499 all of which behave the same. This is the innermost, lower bulb in the taillight cluster. The one thing that looks off to me is that the socket has offset posts (not at 180 degrees) while the bulbs all seem to be at 180 degrees, but I can't seem to be able to get pics or details on amazon that makes it clear what I am ordering. Who thought replacing a bulb would be such a PITA.

What you are experiencing can happen if you put in the wrong Watt bulb. Those from an auto store come in 4 Watt and 5 Watt with the same number. Make sure you have the correct wattage bulb. I think the brake bulb is a 4 watt but don't take my word for it.

The brake light bulb has two filaments, 4 or 5 watt for the tailight and 20 watt I think for the brake light. Porsche has a special part number for it, but I know I've used ones bought from an auto parts store successfully. The Porsche owners manual has the bulb numbers and wattages.

Sorry but there is no 20 watt bulb in the tail or brake light. From the owners manual...."Tail light, rear fog light, brake light, tail light.........P21, 4 W". Also, "Tail light, reflector......P21, 5W".

I went thru the same conundrum. Mainly the ‘specified’ bulb had the prongs in the wrong location. Double-check the wattage on the bulb. Then verify the needed post position. Then go to your auto parts store and you an look for a bulb that hatches what you need. It may not be the ‘number’ that you think you are needing. Or, use an online specialist retailer such as Suncoast .

I know, that reference is confusing. But obviously the brake light has more wattage (brighter) than the tail light, in most cars it's about 20W. Maybe the "P21" refers to the brake light output.

Also make sure it's a silver based (nickel plated) bulb.. that can make a difference in the bulb-out warnings (learned that in BMWs..)

FWIW I have tried both 4w and 5w bulbs (both had double filament) and all with silver/nickel bases. The manual said P21/4 but that was not specific enough to order. I had pulled the specific model numbers off suncoast but ordered from Amazon . I am thinking it must be something about the post placement. The posts at 180 deg did go in but clearly something is not right. I am going to try going in to the local autoparts store for the next pass to try to make sure I get a bulb with the offset posts since it does not seem possible to specify that ordering online

when I had to replace a brake light I could not get the warning light to stop until I replaced both of them with the same type/brand of replacement bulb

After visiting both O'Reilly auto parts and autozone and not being able to find the right bulbs at either place I have given up and ordered the genuine Porsche bulbs from Pelican . About a 10 day wait though.

I've been simply going to my nearest Porsche dealership, walking up to the parts department, and buying bulbs I need. I claim my 10% discount as a Porsche Club of America member and the pricing isn't outrageous. Plus the parts guy looks up the right bulb every time to make sure it's right. Fortunately, the dealership is only about 10 miles away.

i have replaced 2 of these with the autozone (other big box ) replacement but you need a file i file off the detent that is "higher" on the bulb closer to the glass not sure why i have a file in my trunk but it lives there now this seems like a very not porsche guy like fix but i cant justify the cost plus shipping time been a few years on the first bulb and its fine hope this helps someone that is frustrated and wants to fix it now think the correct part is 1157 bulb if you can find it