BMW 5 Series: N20 Petrol Timing Chain and Guide Failure

The N20 2.0-litre turbocharged four-cylinder fitted to 520i and 528i models uses a timing chain with plastic guides and a hydraulic tensioner that wear prematurely. The chain can stretch, the guides fracture, and the chain can jump or skip teeth on the camshaft sprocket. If the chain jumps timing, valve-to-piston contact occurs immediately, causing catastrophic internal engine damage. BMW issued a service action bulletin for inspection and replacement of affected components.

• Rattling or ticking noise from front of engine on cold start that may clear when warm
• Check engine light with camshaft position or correlation fault codes
• Engine misfires or runs roughly on multiple cylinders
• Sudden loss of power or complete engine seizure without prior warning

1. 1

   Listen carefully for timing chain rattle on a cold start with the engine at idle — the noise may come from the front of the engine and diminish as oil pressure rises.

2. 2

   Scan for fault codes P0016, P0017, P0340 or related camshaft sensor correlation codes.

3. 3

   Request BMW dealer records and check for any service action or bulletin work carried out.

4. 4

   A specialist inspection of chain tension and guide condition is mandatory on any N20 engine above 80,000 km.

Parts involved: Timing chain.

$3,500 to $9,000 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 or guides been replaced or inspected by a BMW dealer?”
• “Has any service action or recall work been carried out on the engine?”
• “Does the engine make any rattling noise during the first few seconds after a cold start?”

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.