Balance shaft gear wear
Attaches to M271-KOMP at engine level · Engine · carried by 2 variants across 2 chassis
Overview
Balance shaft gear wear is a common fault recorded against M271-KOMP at engine level, typically from 100–200k km. It shows up as check-engine light with camshaft/crankshaft correlation codes, rough running, and eventually a car that won't start. Where it's documented, the repair runs €2,500–€4,500 (engine out at a specialist, costs dated 2026-07), and it can be partly checked before you buy. 2 variants across 2 chassis in this database inherit it.
What happens
Symptom. Check-engine light with camshaft/crankshaft correlation codes, rough running, and eventually a car that won't start.
Cause. The balance-shaft gear was manufactured too soft on a range of early engines and wears against the crank gear until timing is lost. Mercedes revised the part.
Later parts. Revised gear; not present on the M271 EVO from the 2011 facelift
Sources. Mercedes technical documentation · specialist reports
How to check it
OBD scan
Scan for correlation codes before anything else. A clear scan today doesn't clear the car, but codes present are decisive. Ask for a balance-shaft repair receipt with the revised part number; engine number ranges are published and a specialist can check yours.
Mandatory. A seller who refuses a scan has answered the question.
Every variant that carries this
| Variant | Chassis | Body | Years | Risk | Good buy | Cost as % of good buy |
|---|---|---|---|---|---|---|
| C 180 Kompressor M271-KOMP | W204 | sedan | 2007–2011 | R5 | €3,450 | 101% |
| C 180 Kompressor M271-KOMP | S204 | wagon | 2008–2011 | R5 | €3,650 | 96% |
The last column is the point. The same repair is an inconvenience on one variant and a reason to scrap the car on another. A failure costing a quarter of the vehicle's value changes the purchase decision regardless of how rare it is.