Parts for your 2016 Toyota Prius-Sump plug washers

2016 Toyota Prius sump plug washers: what they do and when to replace them

According to Toyota’s own technical documentation, the 2016 Toyota Prius (XW50, 2ZR‑FXE) absolutely uses a sump plug washer, also called a drain plug gasket. The Toyota Repair Manual (TIS) procedure for engine oil replacement specifies installing the drain plug with a new gasket and torquing it correctly, and the Toyota Electronic Parts Catalogue lists the gasket as P/N 90430‑12031 (12 mm aluminium crush washer). The documented torque for the drain plug with a new washer is 39 N·m (about 29 ft‑lb).

On this Prius, the sump plug washer is a soft, crush-type ring that deforms slightly when tightened. That tiny bit of “give” creates a reliable seal between the drain plug and the alloy sump, keeping oil in and road grime out. It also helps the plug reach the correct clamping force without chewing up threads—handy on an aluminium sump, especially in Aussie and Kiwi conditions where hot–cold cycles and long highway runs are common.

Toyota directs replacing the washer at every engine oil change. Reusing a flattened washer can lead to weeping around the plug, undertray drips, or that faint hot‑oil whiff after parking. A fresh 12 mm aluminium (or quality copper) crush washer is cheap insurance, particularly on a hybrid that spends plenty of time heat‑soaking after shut‑down. Sticking with the genuine 90430‑12031 or an equivalent-spec washer keeps things drama‑free.

Tell‑tale signs it’s time (or that the washer’s been reused): dampness around the drain plug, oil spotting on the driveway, or a plug that seems to need more grunt than it should. Don’t overdo the spanner—if it won’t seal at 39 N·m with a new washer, the fix isn’t “more torque”, it’s “new washer and clean mating faces”.

1. Drop the undertray as needed and drain warm oil.
2. Remove the old washer from the plug—don’t stack washers.
3. Clean the sump seat and plug flange.
4. Fit a new 12 mm crush washer (90430‑12031).
5. Install and torque the plug to 39 N·m.
6. Refill with the correct grade, run, and check for leaks.

For peace of mind, keep a couple of spare washers in the glovebox or tool roll. They’re small, inexpensive, and recyclable (aluminium), making them an easy win at each service.

Popular questions

What size sump plug washer does a 2016 Prius use?

It uses a 12 mm crush washer on an M12 drain plug. Toyota’s listed part is 90430‑12031, an aluminium gasket designed to deform slightly for a proper seal.

Quality aftermarket 12 mm aluminium or copper crush washers also work, provided they match the thickness and sealing profile of the original.

How often should the sump plug washer be replaced on a 2016 Prius?

Every engine oil change. Toyota’s service procedure calls for a new washer each time the plug is removed and refitted.

Replacing it prevents slow seepage, keeps the undertray clean, and lets the plug be torqued correctly without over-tightening.

What’s the correct torque for the 2016 Prius sump plug?

39 N·m with a new crush washer installed. That spec is from Toyota’s repair manual for the 2ZR‑FXE engine.

Always clean the mating faces and avoid reusing old washers—over‑torquing to “chase” a seal can damage the sump threads.