Why does my Alfa Romeo Stelvio go into limp mode with 'Service Electronic Throttle Control'?

Short answer: On the Stelvio's 2.0L turbo, 'Service Electronic Throttle Control' plus a sudden loss of power usually means the engine computer saw a problem and put the car in limp mode (reduced power to protect the engine). The most common code owners report is P0299, turbo underboost (the turbo isn't making the boost the computer expects). Owners on Stelvio Forum traced it to worn wastegate linkage on the turbo (the arm that controls boost), a weak battery, and sometimes the fuel pump or the fuel cap. There's also a recall, 25V586, for a fuel pump that can fail.

Symptom: A 'Service Electronic Throttle Control' message and check engine light, sudden low power, often when accelerating on the freeway, and the car feeling normal again after a restart.

What to check first

1. Run your VIN for recall 25V586 (fuel pump) at nhtsa.gov/recalls.
2. Read the codes. P0299 means turbo underboost. Note any other codes too.
3. Test the battery. One owner's battery was down to about 9.8 volts. Low voltage confuses these cars.
4. Have the wastegate linkage checked for play. A worn arm or post lets the wastegate flap, and the turbo can't build boost.
5. Check the fuel cap seal. One owner said a new fuel cap fixed theirs.

Likely causes

1. Worn turbo wastegate linkage. On Stelvio Forum, a 2018 Ti owner's final fix was wastegate linkage with too much slack. The dealer suggested a new turbo instead.
2. Weak 12-volt battery. A 2019 owner with daily limp mode said an AGM H8 battery fixed it.
3. Fuel pump (including recall 25V586). Another owner's dealer replaced the fuel pump and tank. The 25V586 recall covers fuel pumps that can fail on 2018–2019 Stelvios.
4. Fuel cap, ground connections or intake air sensor. Owners also mentioned a fuel cap, cleaning grounds and the smart alternator sensor, and an intake air temperature sensor.

What it usually costs

On Stelvio Forum, owners said an aftermarket wastegate arm ran about $150 (later about $30), while the dealer route is a new turbo. One owner said a fuel cap at about $161 fixed theirs.

Is it safe to keep driving?

Limp mode limits power, which is dangerous when merging or passing. If it happens, move to a safe lane, get off the freeway and have it checked. A failing fuel pump can cut power completely. Verify with a mechanic.

DIY or shop?

DIY for the battery and fuel cap. Shop for wastegate linkage, fuel pump and turbo work.

Recalls, bulletins and complaints in plain words

• Recall 25V586 (2017–2019 Giulia and 2018–2019 Stelvio): the fuel pump may fail, which can cause a loss of drive power. Dealers replace the fuel delivery module. Owners got interim letters in October 2025, and FCA expected the final fix around July 2026, so ask the dealer whether parts are available. If your vehicle is part of this recall, the dealer fixes it for free.
• Recall 21V878 (2020–2021 Stelvio and Giulia, separate issue): the fuel line sensor housing may crack and leak fuel. If your vehicle is part of this recall, the dealer fixes it for free.
• NHTSA complaints: 35 keyword-matched complaints for Alfa Romeo Stelvio 2018–2020 (of 174 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-18; keywords: throttle, limp, loss of power, lost power, turbo, reduced power, service electronic).

What owners report

• In 2018 Stelvio going into limp mode on freeway on Stelvio Forum, a 2018 Ti owner at about 95,000 miles got 'Service Electronic Throttle' and a check engine light when accelerating on the freeway, with P0299 and other codes. Members pointed to wear in the turbo wastegate linkage, which the dealer wanted to fix with a new turbo. Another owner's dealer replaced the fuel pump and tank. The original poster's final answer was slack in the wastegate linkage.
• In Electronic throttle error & limp mode., a 2019 owner had daily limp mode with P0299. Replies included a weak battery at 9.8 volts fixed with an AGM H8 battery, an aftermarket wastegate arm at about $150 (later about $30) instead of a new turbo, a fuel cap at about $161, cleaning grounds and the smart alternator sensor, and an intake air temperature sensor.

My take

My advice as a former lot tech: when a European car throws a bunch of warnings at once, test the battery before anything else. On a Stelvio with P0299, the next stop is a hand on the wastegate arm. Both are cheaper than a turbo.

Vehicle focus: 2018–2020 Alfa Romeo Stelvio with the 2.0L turbo four-cylinder.

Safety / mechanic note

Limp mode or a failing fuel pump can cut power in traffic. Verify with a mechanic.