Description
Siemens Control Unit for Citroën C5 2.0 HDi (RHR)
This Siemens ECU (Engine Control Unit) is designed for PSA diesel applications and is commonly referenced by part numbers such as 9655534080 and 5WS40264D‑T. It is a direct-fit electronic injection control module that manages fuel injection, turbo boost, and emission-related functions on the 2.0 HDi RHR engine. Ideal for professional workshops and experienced DIY mechanics who search by product code, this unit restores reliable engine management when the original ECU is faulty or non‑responsive.
Key Benefits
– Direct replacement option for vehicles equipped with the Siemens SID 803A family ECU.
– Recognizable by multiple OEM references—frequently searched by part number for fast identification.
– Restores precise control of fuel injection timing, injection quantity, and boost management to improve startability, drivability and emissions control.
Technical Information
- Manufacturer: Siemens
- Model: Citroën C5 2.0 HDi (Engine Code: RHR)
- Product Codes: 9655534080, 9661618180, 5WS40264D‑T
- Additional Numbers: 1940YR, 1942YS, 1942X4, 1940X6, NFP
Compatibility Notes
This ECU is identified by the listed product codes and intended for the Citroën C5 2.0 HDi with RHR engine. The same ECU hardware can appear across several Stellantis models that share the RHR engine and matching part numbers; always verify that the part numbers on the unit match the numbers required for the vehicle to ensure fitment.
Installation Recommendations
– Before starting, disconnect the vehicle battery and wait at least a few minutes to avoid accidental short circuits.
– Locate the ECU (position may vary by model year — commonly in the engine bay or behind protective panels); remove electrical connectors by releasing locking tabs and unbolt the unit from its mounting.
– Fit the replacement unit in the original orientation, secure mounting bolts to the manufacturer’s torque where applicable, reconnect all plugs and ensure connectors are fully engaged.
– After mechanical installation, ECU may require coding/initialization to match vehicle immobiliser and engine parameters (see Installation and Coding – Important below).
Why This Part Most Frequently Fails
Common causes of ECU failure on these units include water ingress or moisture exposure, corrosion of connector pins, damage from battery voltage spikes or improper jump starting, and thermal stress leading to solder joint cracks on the PCB. Electrical faults elsewhere in the vehicle (faulty alternator, battery or short circuits) can also damage the ECU if not addressed.
Installation and Coding – Important
- Unit Is Used And Is “Paired” With The Original Vehicle (VIN/PIN/Keys).
- Options To Make The Unit Operational:
- Cloning Data From The Old Unit (EEPROM/Flash) – After Cloning The Unit Is Plug And Play.
- Virginization And Subsequent Initialization/Telecoding Via DiagBox (Or Online) + Key Adaptation.
- It Is Recommended To Be Performed By A Specialist With PSA Service Equipment (DiagBox/Lexia/PP2000).
- Always Disconnect The Battery Before Removal/Installation And Follow The Manufacturer’S Procedure To Avoid Damaging The Unit.
If you need a reliable replacement ECU for a Citroën C5 2.0 HDi RHR, check the product codes listed above and order the matching unit to minimise downtime. For professional workshops, this ECU restores correct management of fuel delivery and turbo control, returning the vehicle to factory‑like operation when installed and coded correctly.
