BMW Petrol Engine – Timing Chain Problems
Premature timing chain failure has become a serious problem for many BMW owners – the issue has been featured on BBC Watchdog and is regularly discussed in BMW forums and other media sites.

Most commonly affecting the 2.0 litre diesel with the N47 engine, we also regularly rebuild damaged engines in the 3.0 litre diesel range, BMW petrol engines and also BMW Minis

A range of BMW petrol engines in cars registered between 2001 to 2015 appear to have a design problem affecting the timing chain or tensioner. The engine timing chain is very weak – it stretches over time, and ultimately snaps.

The tables below detail the affected models and engine codes:

BMW Petrol engines N42 / N43 from 2001 to 2011
Model No. Year Registered Engine Code
116i, 120i, 316i, 320i 2001, 2002, 2003, 2004,
2005, 2006, 2007
N42B18 or N42B20
116i, 120i, 316i, 320i 2007, 2008, 2009,
2010, 2011
N43B16 or N43B20


BMW Petrol engine N20 from 2011 to 2015
Model No. Year Registered Engine Code
125i, 220i, 225i, 228i, 320i,
328i, 420i, 428i, 520i, 528i,
X1, X3, X4, Z4
2011, 2012, 2013, 2014, 2015 N20B20

What Happens When A Timing Chain Snaps?
When a BMW engine timing chain snaps, the inlet and exhaust valves collide with the pistons, resulting in massive engine damage. At this point it will bend all 16 valves, shatter the rocker arms, snap and distort both camshafts and the camshaft housing.

Engine Rebuild Process
Repairing the severe engine damage is a labour intensive and expensive job . We must remove the entire engine and strip down all engine components to identify and replace all damaged parts.
The damaged engine is rebuilt with genuine BMW components including modified chains, guides and tensioners to reduce the risk of a repeat failure.

Engine Rebuild Costs
If your timing chain has snapped then you will require the full engine rebuild procedure, which we offer from £2,500 inclusive of parts.
Each damaged engine is individually assessed – depending on damage to engine parts, and fluctuations in BMW component pricing, the price may be higher.

The History of BMW Timing Chain Failure
Early in 2013 our workshop owner was contacted by researchers from the BBC Watchdog program. The Watchdog researchers were keen to acquire real-world professional advice on this subject – some of our engine rebuild customers had recommended us to BBC Watchdog as experts in this subject.

BBC Watchdog were producing a feature on the BMW timing chain failure issue, having been alerted by many unhappy BMW owners. Some of the BMW owners contacting Watchdog had been quoted huge repair costs from BMW and had instead chosen Prestige to rebuild their badly damaged engines. You can view their report on the BBC website here:

BBC Watchdog Report – BMW Timing Chain Failure

Cheaper Engine Repair Options
If you are considering other companies offering so called ‘re-manufactured’ engines at under £2,000, our advice is to steer clear or do some thorough research. The chances are, the engines are not rebuilt, nor re-manufactured, as genuine BMW replacement parts cost over £1,200.
It is more likely that the replacement engine will have been recovered from a damaged car – it’s also likely that it won’t have the modified BMW replacement timing chains, guides and tensioners – so they will just snap again…

It is a skilled and time consuming process to correctly repair an engine damaged by a broken timing chain, cheap solutions are unlikely to provide the reliability and warranty offered by Prestige.