P0017 on BMW: How to Diagnose & Fix

The BMW S55 twin-turbo inline-6 engine has a critical design vulnerability where the crank hub is secured only by a single bolt with friction material - no keyway or mechanical lock. Under high load conditions such as aggressive downshifts, hard acceleration, or increased boost from tuning, the crank hub can slip. When this occurs, camshaft timing is thrown off and can cause catastrophic engine damage.

The N20 turbocharged four-cylinder in E84 X1 models is prone to premature timing chain guide wear and failure. Plastic chain guides become brittle and can break, causing chain slack, jumped timing, and potential catastrophic engine damage. Most failures occur between 60,000-100,000 miles.

The N20 four-cylinder engine in the 1 Series is prone to premature timing chain stretch and guide failure, particularly in models built before 2015. The plastic chain guides become brittle over time and can break apart, allowing chain slack that leads to jumped timing. This can cause catastrophic engine damage if the chain skips enough teeth.

The 4.4L twin-turbo N63 V8 in the X6 xDrive50i is known for timing chains that stretch and wear early. Cars.com reported that BMW issued service bulletin 11 16 14 because N63 timing chains "have been found to stretch and wear out prematurely," which leads to premature valvetrain wear and reduced engine performance. The bulletin covers N63 versions of the X6, X5, 5, 6 and 7 Series, among others, including the ActiveHybrid X6. For the X6, it applies to E71 models built from July 2008 to June 2014. A stretched chain throws off valve timing, and owner guides note this can reduce torque and throttle response. BMW handles the issue through the N63 Customer Care Package (SI B00 13 14). As part of that package, a dealer uses BMW's diagnostic software to measure chain stretch. The car is then reprogrammed to a shorter oil-change interval of 10,000 miles or 12 months, which BMW says is needed to avoid future valvetrain wear. Later F16 X6 xDrive50i models (2015-2018) are not on the bulletin's list of affected build dates.

The M2 Competition uses the same S55 engine as the F80 M3 and F82/F83 M4, with the same crank hub design. The crankshaft, a friction disc and the timing sprocket are not keyed together. A central bolt clamps them, and that clamping friction is the only thing holding the cam timing in place. A hard load or sudden shock can overcome the friction, and then the timing sprocket turns separately from the crank. Aggressive downshifts, hard launches, repeated high-rev track use and remaps that bring in torque early are all linked to it. Launch control has been linked to failures on otherwise standard cars. The crank bolt can also loosen over time. Once the timing jumps, valves and pistons can collide, and the engine can be badly damaged or destroyed. On a stock car driven on the road, specialists say failure is rare but not unheard of. The risk goes up on remapped, tracked or hard-driven cars: some UK specialists estimate that about 1-2% of remapped S55s slip over time, and more on track cars. BMW has issued no recall or service bulletin. The S58 engine that replaced the S55 (G80 M3, G87 M2) uses a one-piece keyed hub.

The S55 engine in the F82/F83 M4 (2015-2020), which is also used in the F80 M3 and M2 Competition, has a factory crank hub that is not keyed to the crankshaft. The timing parts are held in alignment only by friction washers and the clamping force of the central crank bolt. Under high load, hard launches or sudden throttle changes, those friction surfaces can slip. When that happens the engine falls out of timing, and if it moves far enough the pistons can hit the valves, which can ruin the engine. Tuned and tracked cars are discussed most, but specialist shops also report hub failures on cars at stock power in normal driving. BMW has not issued a recall or service bulletin for it, so the problem is known mainly through owner reports and aftermarket specialists.