In the past, diesel injectors were considered as plug and play. The introduction of more advanced systems (Common Rail injectors) means that the garage cannot be sure whether the injector needs coding or not.

Common Rail diesel systems offer a number of advantages over traditional diesel systems such as better performance, lower fuel consumption, and quieter engine flow. Another significant advantage of the Common Rail System is its ability to substantially reduce emissions, which is the buzzing phrase on the lips of every eurocrat.

So why the injector code? The injector code, typically known as the IMA code (Bosch and Siemens) or the calibration code (Delphi), is a code that is programmed on the ECU for accurate communication and injection control. With the ever-so increasing emission legislation and tightening of limits, vehicle manufacturers have been forced to control the flow of fuel entering the engine more precisely to optimize the efficiency of the combustion process and regulate emissions within acceptable limits…

IMA (Injector Menge Abgleichung / Injector Quantity Offset) coding is an industry standard. When the injector passes the OE test, it generates an IMA code that identifies where the needle and nozzle assembly is adapted in the tolerance range, allowing the ECU to change fuel accordingly and optimize engine performance. Failure to encode the injectors can result in several problems:

Performance - In some systems, it may be possible to drive without noticing any difference. In fact, if the injectors have not been coded, it is unlikely that the customer will achieve optimal vehicle performance. Faults can occur after some time.

No start - In newer systems, if you do not enter the injector codes, the vehicle will not start

Low performance / irregular engine running - because the injectors are not coded, the ECU will continue dosing as if the previous injector was still present, which could cause poor performance.

How do I know if the injector I purchased needs coding?

DELPHI Common Rail Injectors - Always require engine coding. Typical code is 16 alphanumeric characters (C2i injectors) or 20 characters for newer applications (C3i injectors). The code is usually located on the injector head.

DENSO Common Rail injectors - generally all require coding, although some very early versions may not. A typical code length is 16-24 alphanumeric characters depending on the vehicle make. The code is usually found on the injector connector. You can also use the QR code found on the injector for this information.

VDO / Siemens Common Rail Injectors - Only VW applications require coding at this time. The typical length is 6 digits and is located on the injector head.

BOSCH Common Rail Injectors - generally all require coding, although some older versions may not. In simple terms, if the IMA code is present, then the injector will need coding. The typical code length is 6-10 digits and is located on the injector connector head.

N.B. - The above coding information applies to new diesel injectors. A remanufactured injector, if purchased from an authorized service technician, will also have a new calibration code that is usually affixed to the injector as a sticker or label. This code is also placed on the output test report.