MercedesBenz A-Class A45 AMG Engine Replacement - Compare Prices & Get Quotes

A replacement engine for an A45 AMG typically costs between £2,000 and £15,000 depending on the engine code and condition. Used M133 units start from £2,000-£4,500, reconditioned from £4,500-£8,000, and fully rebuilt M139 engines from £8,000-£15,000. Labour for supply & fit adds £600-£1,200 for AMG-specialist work.

• Used M133 (W176 A45): £2,000-£4,500
• Rebuilt M133 (W176 A45): £6,000-£12,000
• Rebuilt M139 (W177 A45): £8,000-£15,000

All A45 AMG engines use timing chains, not belts. The M133 (W176) and M139 (W177) both have timing chains designed to last the life of the engine with proper maintenance. However, the M133 is known for timing chain stretch on higher-mileage units - a rattling noise on cold start is the classic warning sign.

• All A45 AMG engines: timing chain
• M133 chain stretch common at 40k-120k miles depending on use
• Regular oil changes are critical for chain longevity

Common signs of engine problems in the A45 AMG include: a rattling noise on cold start (timing chain stretch on M133), misfires or rough running (valve spring failure on M139 or ignition coil failure on M133), power loss or whistling from the engine bay (turbocharger issues), and overheating after spirited driving (cooling system strain on M139). If you experience any of these, have the car inspected immediately.

• Rattling on cold start - timing chain (M133)
• Misfires - valve springs (M139) or ignition coils (M133)
• Power loss - turbocharger or carbon buildup

It depends on the generation and condition. A W176 A45 AMG is typically worth £10,000-£25,000 - a rebuilt M133 engine (£6,000-£12,000) can be a worthwhile investment if the car is in good condition. A W177 A45 AMG is worth £20,000-£45,000 - a rebuilt M139 engine (£8,000-£15,000) is usually well within the car's value. For lower-value examples or those with multiple issues, a specialist repair (timing chain, valve springs) may be more economical than a full replacement.

• W176 (2013-2018): rebuilt M133 viable for good condition cars
• W177 (2019-present): rebuilt M139 usually justifies cost
• Vehicle worth over £15,000: replacement usually justifies the cost

The M133 is the original 2.0-litre AMG engine used in the W176 A45 AMG (2013-2018), producing 360-381 hp with a twin-scroll turbocharger. The M139 is the successor introduced in the W177 A45 AMG (2019-present), producing 382-416 hp. The M139 features a rotated engine layout (turbo and exhaust at the rear), higher boost pressure (up to 2.1 bar), combined direct and port injection, and a higher rev limit of 7,200 rpm. Both are hand-built under AMG's "One Man, One Engine" philosophy.

• M133: 360-381 hp, W176 (2013-2018)
• M139: 382-416 hp, W177 (2019-present), rotated layout, higher rev limit
• Both: 2.0L, hand-built, twin-scroll turbo

On M133-equipped A45 AMG models (W176, 2013-2018), misfires are most commonly caused by ignition coil failure or carbon buildup on intake valves. On M139-equipped models (W177, 2019-present), misfires are often caused by broken valve springs within the cylinder head. Faulty spark plugs or clogged fuel injectors can also cause misfires on both engines.

• M133 ignition coil failure - common; replace coils
• M139 broken valve springs - cylinder head inspection required
• Carbon buildup - direct injection engines; walnut blasting recommended