A2661531491 / A0034466040 / 5WK90990 ECU Mercedes A-Class Engine Control Unit.

Product Description
The Engine Control Unit (ECU) with OEM part numbers A2661531491, A0034466040, and 5WK90990 is a genuine Mercedes module used in various A-Class models. This ECU (also known under the SIM266 hardware architecture) governs essential engine functions such as fuel injection, ignition timing, throttle control, diagnostics, and emission regulation. When properly programmed with your vehicle’s VIN and immobilizer data, it delivers optimal engine performance and system integration.

This unit is typically offered in used, refurbished, or remanufactured condition. Before installation, confirm pinout, software version, and immobilizer compatibility. A skilled technician should handle reprogramming or cloning to ensure correct integration with your car’s systems.

Common failure symptoms include intermittent stalling, no-start conditions, error codes like P0605 or P0606, or loss of ECU communication. Many rebuilders offer variant or clone services to rematch your ECU.

Compatibility Table

Vehicle Make	Model / Platform	Engine / Variant	Production Years	ECU Part Numbers / Comments
Mercedes-Benz	A-Class (W169, W176, etc.)	1.5 L / 1.7 L petrol (SIM266 variants)	~2009 – 2012 (and adjacent years)	A2661531491 / A0034466040 / 5WK90990
Mercedes-Benz	Other small / compact models using SIM266 ECU hardware	(varies)	—	Cross reference may exist for models sharing SIM266 architecture

Compatibility Table

Vehicle Make	Model / Platform	Engine / Variant	Production Years	ECU Part Numbers / Comments
Mercedes-Benz	A-Class (W169, W176, etc.)	1.5 L / 1.7 L petrol (SIM266 variants)	~2009 – 2012 (and adjacent years)	A2661531491 / A0034466040 / 5WK90990
Mercedes-Benz	Other small / compact models using SIM266 ECU hardware	(varies)	—	Cross reference may exist for models sharing SIM266 architecture

Shipping, returns and warranty

Worldwide shipping with tracking
30-day returns on unused, uninstalled parts
90-day limited warranty against defects

Send us your VIN and we confirm fitment before shipping. See our shipping policy and return policy.

A-Class (W169

A2661531491 Mercedes A Class A0034466040 ECU Engine Control Unit 5WK90990