ECU 55255943 – what to know
We offer a working MJD 8F3.X3 unit (Magneti Marelli) with part number 55255943. It controls the engine of the Fiat 500 1.3 Multijet. We test every unit before dispatch.
Tests, options and warranty
- Every ECU is tested on the bench and fitted to our test car before dispatch.
- Paid extra options: EGR OFF and DPF OFF.
- Warranty: 6 months.
Symptoms that may point to an ECU failure
- Diagnostics cannot connect to the ECU.
- The engine will not fire, the injectors get no signal.
- The fault appeared after water got in or after a short in the harness.
- The ECU has no power despite working fuses.
The cause may also be the wiring, the power supply or a sensor. Diagnose first, then buy.
Choose by part number
This unit comes from a Fiat 500 1.3 Multijet. We match these ECUs by part number only, because the version is decided by the number, not by the MJD 8F3.X3 type alone. Number 55255943 on your label must match the number of this unit.
Virgin or IMMO OFF
- Virgin – Plug & Play: after fitting, the ECU codes itself to the car and immobiliser, no programming needed. Condition: matching part number and a working immobiliser.
- IMMO OFF on request: the car runs correctly, but a red immobiliser warning appears on the dashboard and a fault is stored in diagnostics that cannot be cleared without pairing with the immobiliser. The Virgin version does not have this fault.
Label data of ECU 55255943
- Part number: 55255943
- ECU type: Magneti Marelli MJD 8F3.X3 / MJD8F3.X3
The type may be written with a space (MJD 8F3.X3) or without it (MJD8F3.X3) – it is the same type.
More units in the Fiat engine ECU category and on the FPT manufacturer page.
Similar numbers from this family: 51908941 MJD 8F3.Q3, 55261314 MJD 8F3.X3, 55259329 MJD 8F3.C3, 55263694 MJD 8F3.QF.
Frequently asked questions about ECU 55255943 MJD 8F3.X3
Does ECU 55255943 fit my car?
Check the label of your ECU: part number 55255943 and marking MJD 8F3.X3. If the numbers match, the ECU fits – the car model alone does not decide this.
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Does the Virgin MJD 8F3.X3 need programming?
No. After fitting, ECU 55255943 codes itself to the car and immobiliser. The condition is a working immobiliser and a matching part number.
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What is the difference between IMMO OFF and Virgin?
With IMMO OFF the car runs, but a red immobiliser warning stays on the dashboard and a fault remains in diagnostics that cannot be cleared. The Virgin version does not have this fault, which is why we recommend it.
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Can I order extra services for ECU 55255943?
Yes, for an extra charge we carry out EGR OFF and DPF OFF. These options are done on request before dispatch.
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