BMW 1 Series: N13/N18 timing chain stretch — cam-crank fault

The N13 (BMW) and N18 (MINI Cooper S) 1.6-litre turbo engines share a Prince architecture timing chain that runs from the crankshaft sprocket up to the intake and exhaust cam sprockets via a secondary balance shaft chain. The primary chain guide and plastic tensioner pads are undersized for the engine's high-rpm tuning. From approximately 60,000 km onward the chain stretches measurably; because the variable valve timing (VANOS) system relies on precise chain indexing, even 2–3 mm of slack introduces cam-to-crank phase error. The ECU stores P0016/P0017/P0341 cam-crank correlation codes, often with no audible rattle. Continued driving with stretched chain risks guide disintegration — plastic fragments enter the sump and oil pump, causing secondary bearing failure. Cold starts are the highest-risk phase as oil pressure builds slowly.

• Engine management light with codes P0016, P0017, P0341 or P0346
• Rough idle that may smooth out once warm
• Hunting or fluctuating idle speed on cold start
• Reduced power and flat torque curve throughout the rev range
• Rattling from front of engine on cold start

1. 1

   Review service history for oil change compliance — the N13 requires 5W-30 LL-01 oil every 15,000 km maximum in real-world NZ/AU conditions.

2. 2

   Inspect the oil filler cap and dipstick for sludge, which indicates oil quality neglect.

3. 3

   Listen at idle for any light chain tick from the front of the engine.

4. 4

   If a workshop inspection is possible: Connect an OBD-II scanner before purchase and check for stored or pending cam-crank codes.

Parts involved: Timing chain.

$2,400 to $5,800 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

• “Has the timing chain, tensioner and guides ever been replaced?”
• “Has the car shown any engine management lights related to cam timing?”
• “What oil change interval has been followed, and using which specification oil?”
• “Has the car been driven with the engine light on for any period?”

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.