Why does my Lexus NX 200t rattle on a cold start?

Short answer: On the NX 200t, a metallic rattle right after a cold start that mostly goes away once the high idle drops is often the turbo's wastegate linkage. The wastegate is a small valve that controls turbo boost, and when its arm wears it can rattle while the engine is cold. It's usually more annoying than dangerous, but get it checked to rule out other causes.

Symptom: A buzzing or rattling noise for the first minute or so after a cold start, mainly while the idle is high, then it quiets down.

What to check first

1. Record the noise on a cold start and where it comes from (the turbo is at the back of the engine).
2. Ask a shop to check play in the wastegate actuator arm. One owner found the noise stopped when the arm was touched.
3. Rule out a loose heat shield or other rattles under the car.
4. Ask a Lexus dealer about any bulletins for your VIN.

Likely causes

1. Worn turbo wastegate actuator linkage. A ClubLexus owner at around 100,000 miles traced the rattle to play in the wastegate arm.
2. Other engine noises such as the vacuum valve. In another ClubLexus thread owners discussed a vacuum regulating valve as a source of engine noise.

What it usually costs

I couldn't find a reliable published price. Costs range from a simple fix to turbo replacement, depending on what a shop finds.

Is it safe to keep driving?

Usually yes if it's only a short cold-start rattle and the engine runs normally. Get it checked if you lose power or get a check-engine light. Verify with a mechanic.

DIY or shop?

Shop. One owner tried brake anti-vibration paste on the linkage as a temporary quiet-down, but the proper fix is a shop job.

Recalls, bulletins and complaints in plain words

• No recall covers the wastegate rattle in NHTSA's data.
• NHTSA complaints: 1 keyword-matched complaints for Lexus NX200T 2015–2017 (of 87 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-17; keywords: wastegate, waste gate, turbo, rattle).

What owners report

• In NX200t waste gate arm noise, an owner at around 100,000 miles said the rattle mostly went away once the high idle dropped. He traced it to play in the wastegate actuator arm; touching it quieted the noise. Another member suggested anti-vibration brake paste as a temporary fix.
• Other owners discussed a loud NX200t start-up and engine noise, where a vacuum regulating valve came up.

My take

My advice as a former pre-purchase inspector: I always asked to hear a turbo car start stone cold. A rattle that goes away in a minute is easy to miss if the seller warmed the car up before you arrived.

Vehicle focus: 2015–2017 Lexus NX 200t with the 2.0L turbo.

Safety / mechanic note

Loss of power or a check-engine light with the rattle needs prompt diagnosis. Verify with a mechanic.