If your car has a confirmed engine ECU fault and you are in London, you do not need to track down a replacement unit to swap in — you need your original unit repaired properly. The engine ECU manages fuelling, ignition timing, boost and emissions, and when it fails it takes the car with it. We are a UK engine ECU repair specialist serving London and the South East from our workshop in Epsom, on the capital’s southern fringe. Every engine ECU, ECM and PCM we take in is repaired in-house at component level, so the unit keeps its original coding and immobiliser pairing and refits straight to your vehicle. This page sets out exactly what we repair, how the mail-in service works for London customers, and why a component-level repair beats a replacement.
What we repair — engine ECUs only
We repair engine control units, and only engine control units — the ECU, ECM or PCM that runs your engine. That single focus is deliberate. It is what our engineers work on every day, across petrol, diesel, hybrid and direct-injection systems, on vehicles ranging from small city cars through to performance models, vans and 4x4s.
Repairs are carried out at component level. Rather than swapping the whole unit, we diagnose and fix the specific fault on the board itself — a failed injector driver, corrupted EEPROM data, dry or cracked solder joints, a failed voltage regulator, or a damaged CAN bus transceiver. Because the original processor and memory stay in place, the ECU retains its coding, immobiliser pairing and security relationship with your car. It goes back in with no reprogramming and no dealer visit.
We do not work on ABS units, airbag modules, instrument clusters or body-control modules — engine ECUs are our sole specialism, and keeping that focus is what lets us repair them well. If you are not certain the ECU is the cause of your fault, our engineers confirm coverage for your exact part number before any work begins, rather than guessing.
Engine ECU, ECM or PCM — what the terms mean
The same component goes by different names depending on the manufacturer and the era of the vehicle, which causes a lot of confusion when people search for a repair. All three sit within our scope.
- ECU (Engine Control Unit) — the general term for the module that governs how the engine runs.
- ECM (Engine Control Module) — the same idea, and the term many manufacturers and diagnostic tools use.
- PCM (Powertrain Control Module) — a combined unit that manages both the engine and the transmission on many vehicles.
Whichever of these your car uses, the failure modes and the repair approach are the same: identify the specific fault on the board and correct it, keeping the original unit and its coding. If your fault code or garage report names an “ECM” or “PCM” rather than an “ECU”, you are in the right place.
How our mail-in service works for London customers
We are a mail-in service by design. There is no walk-in counter, and that is a strength rather than a limitation: every hour goes on the bench, and where you are in London makes no difference to the repair or the turnaround. Whether you are in the City, an inner borough, or an outer suburb, the process is identical.
- Remove the engine ECU from the vehicle, or have your garage remove it, then complete the Repair Form on our website with your vehicle and part-number details.
- Send the unit to our Surrey workshop. Trade customers across London post units to us this way as a matter of routine, and it is straightforward for private owners too.
- We log the unit, inspect it visually, and test it electrically, then run fault-specific diagnostics to find the actual root cause rather than the symptom.
- We contact you with the outcome and an estimated repair price. No chargeable work begins until you have authorised it.
- The component-level repair is carried out under microscope with temperature-controlled rework equipment, and is not signed off until it passes final testing.
- We return the repaired unit ready to refit, with its original coding intact, covered by a 24-month warranty on the repair carried out.
When you send a unit, post the engine ECU on its own — there is no need to include any other parts — and make a note of your registration and the part number printed on the ECU’s label so we can match it to your vehicle quickly. Packaging it well protects the connectors and the board in transit, which matters when a unit is travelling across London and back.
To start, complete the Repair Form on our contact page. Our engineers will confirm they cover your unit and tell you what the diagnosis involves before anything is sent.
Why London drivers and garages send their ECUs to us
The unit that comes back is your own. A replacement ECU bought online or from a breaker has to be coded and paired to your vehicle, which usually means specialist programming or a trip to a franchised dealer. A component-level repair sidesteps all of that, because the original coding never leaves the unit.
Every repair is done in-house by our own engineers, on our own equipment — no outsourcing, no subcontracting, no overseas processing. That matters for accountability: the same workshop that diagnoses your fault stands behind it with a 24-month warranty on the specific repair carried out, so there is a single point of responsibility if you ever need to come back to us. The process is transparent from start to finish, because the unit is tested and diagnosed, you are told the outcome and the estimated price, and nothing chargeable happens without your say-so.
It also matters for accuracy. Engine ECUs fail in specific, recognisable ways, and a structured diagnostic process — logging, inspection, electrical testing, then fault-specific work — finds the true cause instead of masking a symptom. For garages, that means a unit you can refit with confidence and hand back to your customer knowing it has been tested properly. For private owners, it means an honest answer about what has gone wrong and whether it is worth putting right.
Engine ECUs we repair, by vehicle make
Our coverage spans European, Japanese, Korean and American manufacturers, backed by an extensive part-number library. Within each make we cover a broad span of models and engine variants, from everyday hatchbacks and diesels through to vans and performance units, and the library grows as new units come through the workshop. You can browse what we repair by make, or start from the main engine ECU repair hub if you are not sure where your unit fits.
Popular make pages include our BMW engine ECU repair, Audi engine ECU repair, Ford engine ECU repair and Vauxhall and Opel engine ECU repair pages. For the full range, see our engine ECU repair hub and the What We Repair index, which lists every make and unit we cover.
If your make or exact part number is not listed, complete the Repair Form anyway — the technical team confirms coverage for your specific unit rather than leaving you to guess from a menu.
Serving London and the South East from Surrey
We are based in Epsom, Surrey, just outside the London boundary, which puts us within easy reach of the whole South East. For a mail-in repair, though, the exact distance barely matters. A unit posted from Camden, Croydon or Canary Wharf reaches the bench just as quickly as one from our own doorstep, and comes back the same way.
That reach means we serve London drivers and independent garages the same way wherever they are across the capital and the surrounding counties: send the engine ECU in, and receive a repaired, ready-to-fit unit in return. There is no need to be near us, no need to book a slot, and no need to bring the whole car anywhere. For trade customers, that makes us a straightforward extension of your own workshop — a specialist bench for the engine ECUs you would rather not tackle in-house.
Common engine ECU faults we repair
A failing engine ECU rarely fails cleanly. The signs range from a car that will not start or cuts out unexpectedly, through persistent misfires and rough running, to a vehicle that drops into limp mode or throws communication faults that a diagnostic tool cannot clear. Intermittent problems that come and go with heat or vibration are common too, and are often traced back to the ECU.
Underneath those symptoms are specific, repairable faults. Injector and ignition driver failures stop cylinders firing correctly. Corrupted EEPROM data upsets how the unit stores and reads its settings. Dry or cracked solder joints develop from repeated heat cycling and vibration. Failed voltage regulators leave the board without a stable supply, and CAN bus transceiver damage — often after a jump-start or a wiring fault — cuts the ECU off from the rest of the car. These are exactly the faults a component-level repair is built to correct.
If you already have a fault code pointing at the ECU, or a garage has diagnosed the unit as the cause, we can take it from there. If you are still working out whether the ECU is really the problem, our engineers will help you confirm it before you send anything.
ECU repair London: frequently asked questions
Frequently asked questions
An engine ECU fault does not have to mean replacing the whole unit or hunting down a second-hand ECU that then needs coding to your car. If you are in London or the South East, the quickest route back to a properly running vehicle is to have your original unit repaired at component level and returned ready to fit. Complete the Repair Form on our contact page and our engineers will confirm they cover your ECU, explain what the diagnosis involves, and take it from there.