BMW 2 Series: N20 Timing Chain Tensioner Failure and Rattle on Cold Start

The N20B20 2.0T engine uses a hydraulic timing chain tensioner that loses pressure when the engine sits. On cold start, the tensioner requires several seconds to build oil pressure, during which the timing chain can rattle and in severe cases jump a tooth on the guide rail. Extended neglect leads to stretch and guide rail disintegration. BMW issued TSBs and an extended warranty for some markets. This is the single most documented mechanical fault on the N20 engine family.

• Metallic rattling noise on cold start lasting 2-10 seconds from front of engine
• Check engine light with camshaft position or timing correlation fault codes (P0016, P0017)
• Rough idle or misfires that clear once warm
• Reduced power or limp mode in advanced cases
• Visible timing chain shavings in oil on dipstick or during oil changes

1. 1

   Start the cold engine and listen immediately for a metallic rattling or ticking from the front of the engine lasting more than 1-2 seconds.

2. 2

   Check service records for timing chain replacement.

3. 3

   Inspect for oil leaks at the front timing cover.

4. 4

   Pull codes for camshaft position correlation errors (P0011, P0012, P0016, P0017).

Parts involved: Timing chain.

$2,800 to $5,500 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 and tensioner ever been replaced, and do you have workshop invoices?”
• “Has the car ever shown a cold-start rattle or check engine light related to camshaft timing?”

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.