BMW M5 F90: S63 Engine Weak Spots and What to Check Before Buying
Quick Summary
The BMW M5 F90 (2017–2023) is the first all-wheel-drive M5 ever built. Under the hood sits a twin-turbo 4.4-liter V8, the S63B44Tx, rated at 600 hp and 555 lb-ft. The 0–60 mph sprint takes 3.4 seconds. Before buying a used one, checking the service history, the stock tune, and completed recall campaigns is critical.
The Problem
You get into a used M5 F90, press the throttle—and instead of the shove you expected, you get a check engine light or, worse, the smell of fuel. Buyers who skip the history check risk serious trouble: anything from fuel pump failures to a fire hazard. Here’s how to avoid that.
Symptoms
- Check engine light and loss of power while driving
- Fuel smell in the engine bay
- Jerky transmission behavior
- Poor fuel economy (worse than 12 mpg)
- Knocks and detonation under hard driving
Causes
The S63B44Tx is BMW M GmbH’s evolution of its V8: two turbochargers mounted in the valley between the cylinder banks, plus direct injection at 350 bar. That pressure delivers a fine fuel spray and better mixture formation—but it loads up the fuel system.
BMW ran two major service campaigns. In June 2018, a software fault in the engine management could shut down the fuel pump—at worst, that meant power loss or a stalled engine. In August 2019, a defect in the high-pressure fuel pump mounting created a risk of fuel leaks and fire.
Plenty of owners chip-tune these cars. Unauthorized changes to the tune can lead to overheated turbos, detonation, and piston assembly failure.
The Fix
Pre-purchase checks for a used M5 F90:
- Service history. Ask for the service book and verify that scheduled work was done on time. Pay special attention to engine oil and transmission fluid changes.
- Recall campaigns. Make sure every service campaign has been completed—especially the August 2019 one.
- Stock tune. Any non-stock modifications reduce reliability. If the car has been chipped, the smart move is to walk away—or budget for an engine replacement.
- Turbo and exhaust condition. Non-stock components are a reason to negotiate the price down—or to walk away.
ZF transmission service:
BMW’s official schedule doesn’t call for a fluid change in the automatic, but the manufacturer (ZF) recommends one every 8 years or 50,000–62,000 miles. Neglect it and you wear out the torque converter and the solenoids.
Ceramic brakes:
The option costs serious money and only makes sense on track. Ceramics need heat to work at their best and hate aggressive winter road chemicals. For daily driving, steel brakes are the practical choice.
Prevention / Checklist
- Verify the tune is stock before you buy
- Change the ZF transmission fluid every 8 years or 50,000–62,000 miles
- For daily driving: engine and transmission in Sport, suspension in Comfort
- Use the M1 and M2 buttons to store your personal setup presets
- Budget around fuel economy of 17 mpg
The Bottom Line
The BMW M5 F90 is an outstanding sedan, but a used one rewards a careful buyer. Check the service history, confirm the tune is stock, and verify all recall campaigns are done. Do that, and you get a car that delivers every single day.
📖 Full deep-dive: BMW M5 F90: in-depth technical breakdown — control module specifications, engineering nuances, and component subtypes.