What is it Difference between a P21W and P21/5W bulb? Have you had the same problem yourself? You want to replace the indicator light and with great urgency you have fetched a P21W bulb but the bulb does not seem to fit in any way. After a little quiet reading, you find out that you needed a P21/5W bulb. A small difference in text but enough difference to make you have to go back to the shop. Annoying! On this page, we explain the difference between the two bulbs.

P21/5W bulb explanation

A P21/5W bulb is a signal lamp and has multiple uses such as indicator, brake light or tail light. This bulb has 2 filaments, both a 21 watt and 5 watt wire in the same bulb. Here, the large 21 watt wire is for braking or the indicator, for example, and the smaller 5 watt wire is for the parking light. On the side of the fitting are 2 tabs/ pins that should fall into the holder of the car lamp.

P21W lamp explanation

Unlike the P21/5W bulb, the P21W bulb has only 1 filament of 21 watts. This bulb is also a signal lamp and has multiple applications such as indicator light, brake light or rear light. On the side of the socket are 2 tabs/pins that should fall into the holder of the car lamp.

And what if a Y is added?

Did you lamp PY21/5W or PY21W needed? Then you need not a white but a yellow signal light, the letter Y standing for yellow. Or too yellow in English. 

Difference between the two lamps

The differences between a P21W and P21/5W bulb are as follows:

• P21W has 1 filament of 21 watts
• P21/5W has 2 filaments of 21 and 5 watts
• The location of the tabs/ pins on the side are in a different place, see the following image for the difference:

Difference between P21W and P21/5W lamp

Can you change the bulbs yourself?

Changing the bulbs is not very difficult and you can do it yourself. So it is important to determine whether you need a P21W or P21/5W bulb. This can often be easily found on the holder where the bulbs are fitted, but you can of course also just look at the old (defective) bulb, which will undoubtedly also indicate the type. Not sure? Then for most brands we also have a car lights page created where the right lamps can be found.

Ordering signal lamps?

Through our webshop, you can easily order the bulbs you want. We have both the P21W and P21/5W bulbs of the Philips brand available from stock: