Category: Citroen

Citroen engine electronics and the PSA connection
Citroen’s UK line-up leans heavily on the HDi common-rail diesel — the 1.4, 1.6, 2.0 and 2.2 HDi engines that powered the C2, C3, C4, C5, Xsara, Xsara Picasso and the Berlingo, Dispatch and Relay vans, alongside the DS-badged cars. Because Citroen and Peugeot share their engine electronics as part of the PSA group, the control units on these cars are the same Bosch and Siemens references used right across both marques. That is why the Citroen part-number pages beneath this description are filed as shared Citroen/Peugeot units rather than Citroen-only parts: the physical ECU is one and the same, and the failure patterns travel with it.
For the owner or the garage in front of a dead unit, that shared history is good news. These are common, well-documented modules with predictable fault modes, so a fault on a Citroen HDi is a known quantity rather than a one-off puzzle. This page sets out the specific Citroen/PSA references we hold, how they typically fail, how to sort a genuine ECU fault from the things that mimic one, and how the mail-in repair works from start to finish. The Citroen and PSA control units in our library
We file our library by the specific ECU reference rather than the model badge, because the same unit is fitted across several Citroen models and years — and, given the PSA platform sharing, across Peugeot too. The Citroen/Peugeot references we currently repair cover the diesel-led range UK owners search for most, together with the petrol management units:

Bosch EDC15C7 — an early HDi common-rail diesel controller, covered on our Citroen/Peugeot Bosch EDC15C7 HDi common-rail diesel ECU page.
Bosch EDC16C3 — the later-generation HDi common-rail diesel unit; see the Citroen/Peugeot Bosch EDC16C3 HDi common-rail diesel ECU page.
Siemens/Continental SID801 — the Siemens HDi common-rail diesel controller, detailed on our Citroen/Peugeot Siemens SID801 HDi common-rail diesel ECU page.
Bosch ME7.4.4 — the petrol engine-management unit fitted to the smaller petrol cars, on our Citroen/Peugeot Bosch ME7.4.4 petrol ECU page.
Bosch 0261207318 / 9648483480 — the Bosch petrol management unit fitted to the Citroen Xsara Picasso, covered on our Citroen Xsara Picasso Bosch 0261207318 / 9648483480 petrol ECU page.

If the number printed on your unit is not listed here, it is worth checking with us before assuming a match rather than ruling it out — our technical team confirms coverage for a specific ECU instead of guessing, and each part-number page below carries the fault and fitment detail for that particular reference. Where these HDi and petrol ECUs let go
The Bosch EDC, Siemens SID and Bosch ME controllers fail in a fairly small set of recognisable ways, and the majority of what arrives here can be put right on the circuit board rather than needing a whole new module. The complaints we see most often on Citroen units are:

Limp mode — the engine drops into a restricted, low-power state and refuses to rev out, usually because the ECU has lost proper control of an injector or the turbo boost circuit.
Misfire and rough running — uneven running that does not trace cleanly to one cylinder, frequently pointing to a failed injector driver stage inside the unit rather than an injector, coil or plug.
No communication and no-start — the ECU stops answering a diagnostic scan and the engine will not fire, which commonly comes back to a failed communication transceiver or corrupted internal memory.
Non-start after a jump-start or voltage spike — a surge, or a lead put on the wrong terminal while boosting a flat battery, often takes out the ECU’s power supply or an output stage. On these HDi diesels it is one of the most frequent reasons a unit reaches us.
Water ingress and corrosion — moisture reaching the board leaves corroded tracks and intermittent faults; caught early enough, the affected joints and tracks can be rebuilt.
Corrupted EEPROM, failed injector drivers and a failed voltage regulator — specific internal defects that a like-for-like swap would discard needlessly when the actual fault can be corrected.

Where a unit turns out to be beyond economical repair, we also hold exchange units for a number of Citroen/PSA references, so a failed module need not leave the car or van stranded. Telling an ECU fault from the things that mimic it
Engine-ECU symptoms overlap a great deal with sensor, wiring, fuel and battery faults, so it helps to recognise the signs that genuinely point back at the control unit. The clearest are an engine that cranks but never fires, a repeated and sudden drop into limp mode, misfiring with no single-cylinder pattern, warning lights that will not clear, or a unit that has gone completely silent on a scan tool. A fault that appeared straight after a jump-start, a flat battery or work near the ECU connector points strongly at the module itself.
Because each of those symptoms has more than one possible cause, we never treat the ECU as the culprit before it has been tested. Every unit that reaches us is logged, visually inspected and electrically tested before any verdict is reached, so no module is written off — or repaired — on a hunch. Why the original unit is the cleaner fix
A Citroen engine ECU is tied to its own vehicle through the immobiliser and security relationship, which is exactly why dropping in another unit is rarely a straight swap. A replacement, whether new or used, has to be matched to the car, and a second-hand unit brings its own stored pairing that must be cleared and re-linked — diagnostic time and specialist coding on top of the part, with no guarantee it settles first time.
Repairing the original module removes all of that. We correct the specific fault on your own board and return that same unit, so it comes back with its original coding and immobiliser pairing intact. In practice that means a plug-and-play refit — no reprogramming and no re-coding when it goes back on the vehicle, and the engine runs just as it did before the fault. Every repair is carried out in-house by our own engineers, under a microscope with temperature-controlled rework equipment, using only OEM-grade parts that meet or exceed the original specification, and nothing is signed off until it has passed final testing. Sending a Citroen ECU in to us
This is a UK-wide mail-in service, run without a walk-in counter by design. Once your unit arrives it is logged, tested and diagnosed, and we then contact you with the outcome and an estimate before any chargeable work starts — nothing proceeds without your authorisation. The completed repair is covered by a 24-month warranty on the specific fault put right. To get started, find your EDC15, EDC16, SID801 or ME7 reference in the Citroen part-number pages below, or complete the Repair Form on our contact page so our engineers can confirm coverage. The full range of makes and modules we handle is on our What We Repair page.