How to Read an Engine ECU Part Number? Bosch, Siemens, Delphi Label Guide

The most reliable way to choose the right engine ECU is by part number. Two ECUs that look almost identical may have different hardware or software versions. In this guide, we explain what the numbers on the label mean and what should be compared before ordering.

Which numbers are on the label?

An engine ECU label usually carries three types of numbers:

• ECU manufacturer's hardware number (HW): The number assigned by the manufacturer, such as Bosch, Siemens/Continental or Delphi.
• Software number (SW): Indicates the version of the software inside the ECU.
• Vehicle manufacturer's part number: The number used in the catalog of the vehicle manufacturer, such as Renault, Ford, PSA or VAG.

For a compatibility check, at least two numbers should match, preferably the hardware number and the vehicle manufacturer's number.

Bosch label

On Bosch ECUs, the hardware number has 10 digits and is usually written with spaces. 0 281 xxx xxx numbers are mostly diesel (EDC family) ECUs, while 0 261 xxx xxx numbers are gasoline (ME/MED family) engine ECUs. Software numbers usually have 1037 as their prefix. In searches, the spaced (0 281 017 453) and unspaced (0281017453) forms refer to the same product.

Siemens / Continental label

Siemens VDO and Continental ECUs carry 5WS, 5WK, S11… or S18… numbers, as well as SID, SIM, EMS family names. Newer models also use A2C series Continental numbers.

Delphi and Magneti Marelli label

Delphi ECUs commonly have 28xxxxxx format eight-digit numbers and the DCM family name. On Magneti Marelli ECUs, the IAW (gasoline) or MJD (diesel) family names are the most common.

Vehicle manufacturer numbers

• Ford: e.g. 9M51-12A650-BH; the middle part 12A650 stands for engine ECU.
• Renault / Dacia: e.g. 237100xxxxR, numbers with 2371 as the prefix.
• Peugeot / Citroen (PSA): e.g. 96xxxxxx80, 10-digit numbers ending in 80.
• Volkswagen group: e.g. 03C906056H, numbers containing 906 in them.
• Opel: e.g. 55xxxxxx, eight-digit numbers.

Pre-order checklist

1. Take a clear photo of the label on your vehicle's ECU.
2. Note down the hardware number and the vehicle manufacturer's number.
3. Compare them with the “Part Numbers” section on our product page.
4. If you are not sure, send us the photo.

You can go directly to the relevant product by typing the part number, with or without spaces, into the search box on our site. For all options, see our engine ECU products to see what's available.

FAQ

Where is the part number on an engine ECU?

The number is printed on the label on the ECU housing. The label is usually on the top of the housing, and on some models on the connector side. If the label is unreadable, you can take a photo and send it to us.

If the hardware number is the same, can the software be different?

Yes. Two ECUs with the same hardware number may carry different software versions. That is why the vehicle manufacturer's number should also be compared.

Can the ECU be installed if the part number does not match?

If the numbers do not match, the ECU should not be assumed to be compatible with the vehicle. An ECU with a different number may not work or may trigger warning lights.