Mercedes Injector Coding Tool

Sound familiar?

• You replaced one or more injectors and now the engine has a rough idle or shake
• White or black smoke from the exhaust that was not there before
• A check engine light with misfire or fuel system codes after the job
• You moved injectors between cylinders and did not update the ECU
• A shop says they cannot touch it without a dealer level tool

Why this happens

Every Mercedes common rail diesel injector is manufactured with tiny variations in flow. To compensate, each injector is tested at the factory and stamped with a calibration code, usually called the IMA or IQA code, printed right on the injector body.

The engine ECU stores one of these codes per cylinder and uses it to trim the fuel delivery for that exact injector. When you fit a new injector, or even just swap two existing ones between cylinders, the ECU is still trimming for the old part. The result is uneven fueling, which shows up as rough running, smoke, misfire codes and poor economy.

The fix is injector coding: entering each injector's code against the correct cylinder so the ECU knows what it is actually controlling. A basic code reader cannot do it.

What you need to know before you code

How injector coding works with the UCAN-II-D Pro

1. Record the IMA or IQA code printed on each new injector and note the cylinder it is going into.
2. Plug the scanner into the OBD2 port under the dash and switch the ignition on.
3. Run a full system scan and read any stored engine and fuel system codes.
4. Open the control unit list and select the CDI engine control unit, then read its fault memory.
5. Open Adaptations and enter each injector code against its cylinder, confirming each entry.
6. Clear the fault memory, start the engine and confirm the idle is smooth and the smoke is gone.

Prefer to see it first? Our walkthrough is here: How to perform injector coding with a YOUCANIC scanner, and there is a short explainer on what injector coding is if you are new to it.

Your options

	Dealer or shop	UCAN-II-D Pro
Cost	Labor just to enter codes, on top of the parts	$485 once, yours to keep
Doing the job yourself	You still have to get the car there to finish it	Finish the job in your own driveway
Next time	Pay again	Already covered
Other systems	Each one billed separately	SBC reset, Airmatic, AdBlue and more included

More than an injector coding tool

• Full system diagnostics: engine, transmission, ABS, ESP, SRS, body and more
• Bidirectional control and coding
• SBC brake counter reset for C249F
• Airmatic calibration for air suspension
• AdBlue and DEF reset for BlueTEC diesels
• Free updates, no subscription

Why YOUCANIC

YOUCANIC is based in Towson, Maryland, and has been publishing Mercedes repair guides and videos since 2015. The tool is backed by the same team that writes those guides, and support comes from real US technicians, not a call center.

Frequently asked questions

Will this work on my car?
Injector coding applies to Mercedes common rail diesels, including the widely used OM642 V6 and OM651 four cylinder. If your engine takes coded injectors, the UCAN-II-D Pro can enter them. Not sure? Contact us before you buy.

I already use Xentry. Why would I want this?
The menu path is the same, so there is nothing new to learn. This is the tool you can leave in the car, hand to a colleague, or use without tying up a laptop and a licence.

Where do I find the injector code?
It is printed on the injector body itself. Photograph each one before installation, because they are much harder to read once the injector is in the head.

I only replaced one injector. Do I still need to code it?
Yes. The ECU is still trimming that cylinder for the old injector's flow characteristics.

Is there a subscription?
No. You pay once and updates are free.

What if it doesn't work for me?
You have 31 days from delivery to return it, and US return shipping is free.