20 Common Failing ECUs in the UK — Parts, Families & Quick Diagnostic Tips

Modern vehicles rely on dozens of ECUs to manage safety, performance, comfort, and communication systems. Over time, heat, moisture, electrical faults and aging can cause these modules to fail — leaving owners with error lights, drivability issues or complete system shutdowns.

Here’s a practical guide to the 20 most commonly failing ECUs in the UK, with part numbers, ECU family types, and quick checks you can do before committing to replacement.

🚘 1. BMW CAS (Car Access System)

Part No: 6135-6936-921 / 6135-6936-001
Family: Body & Security Control
Quick Check:
✔ Check key recognition errors when starting
✔ Test CAS communication via diagnostic tool

🚘 2. VW/Audi ECU – Bosch MED17

Part No: 03L 906 022 M
Family: Engine ECU (Diesel)
Quick Check:
✔ Read fault codes for injector/sensor errors
✔ Check ECU supply & ground circuits

🚘 3. Ford PCM (Powertrain Control Module)

Part No: 98AB-12A650-AF
Family: Engine/Transmission Control
Quick Check:
✔ Scan for P0600+ communication codes
✔ Verify OBD data stream live values

🚘 4. Mercedes SAM (Signal Acquisition Module)

Part No: A 211 540 07 45
Family: Body & Lighting Control
Quick Check:
✔ Flickering lights / random faults
✔ Test with Mercedes STAR diagnostic

🚘 5. Renault BCM (Body Control Module)

Part No: 28595-S003A
Family: Body & Comfort
Quick Check:
✔ Check central locking & instrument cluster errors
✔ Scan for CAN bus errors

🚘 6. Audi TCU (Transmission Control Unit) – ZF

Part No: 0AW 927 156 J
Family: Transmission Control
Quick Check:
✔ Check shift quality & adaptive learning faults
✔ Read transmission DTCs

🚘 7. Volkswagen DSG ECU – Bosch MG1

Part No: 0AM 927 769 BC
Family: Mechatronics / Transmission
Quick Check:
✔ DSG mechatronics error codes
✔ Monitor clutches and adaption channels

🚘 8. Peugeot / Citroën E‐GRIP ECU

Part No: 9667059880
Family: Engine Management
Quick Check:
✔ Idle/starting issues
✔ Injector and sensor diagnostics

🚘 9. Toyota ABS ECU

Part No: 44510-0E010
Family: Anti-Lock Braking System
Quick Check:
✔ ABS light stored faults
✔ Check wheel speed sensors

🚘 10. Nissan BCM

Part No: 284B7-1LA0A
Family: Body Control
Quick Check:
✔ Intermittent lighting/locking faults
✔ Scan for BCS codes

🚘 11. Land Rover RADAR ECU (Air Suspension)

Part No: LR044713
Family: Comfort & Suspension
Quick Check:
✔ Faulty ride height readings
✔ Test sensor feedback

🚘 12. Honda Immobiliser ECU

Part No: 39820-S5A-D31
Family: Security/Immobiliser
Quick Check:
✔ Immobiliser light on dash
✔ Verify key recognition

🚘 13. Mini (BMW) DME (Engine ECU)

Part No: 75 12 7 134 686
Family: Engine Management
Quick Check:
✔ Misfire codes / poor performance
✔ Fuel trim & sensor checks

🚘 14. Skoda CAN Gateway ECU

Part No: 5Q0 907 530 AD
Family: Gateway/Network Management
Quick Check:
✔ Random communication errors
✔ Check BUS for voltage drop

🚘 15. Volvo SRS Airbag Control Unit

Part No: 30765218
Family: Safety Restraints / Airbag
Quick Check:
✔ Airbag warning light
✔ Check crash sensor circuits

🚘 16. Mazda TCM (Transmission Control)

Part No: BBM3-18-881A
Family: Transmission
Quick Check:
✔ Harsh shifts or limp mode
✔ Read adaptive transmission data

🚘 17. Subaru ECU (Bosch ME7)

Part No: 22611AA710
Family: Engine Management
Quick Check:
✔ O2 sensor & MAF codes
✔ Live data sensor checks

🚘 18. Fiat Body Computer

Part No: 51880669
Family: Body / Comfort
Quick Check:
✔ Light cluster & locking issues
✔ CAN bus communication check

🚘 19. Jaguar InControl ECU

Part No: C2D32731
Family: Telematics / Infotainment
Quick Check:
✔ Connectivity errors
✔ Check CAN and power supply

🚘 20. Tesla MCU (Media Control Unit)

Part No: 1041752-00-E
Family: Infotainment / Control
Quick Check:
✔ Frozen screen / reboot loops
✔ Inspect power & storage hardware

🛠️ Before You Replace — Do These Quick Checks

Many ECU issues are not hardware failures but are caused by:

✔ Loose / corroded connectors
✔ Low battery voltage / bad grounds
✔ CAN bus communication errors
✔ Faulty sensors triggering ECU faults

🔎 Quick Pre-Repair Checklist:

1. Inspect ECU connector pins & harness

2. Check battery voltage & alternator health

3. Scan all modules for communication errors

4. Check related sensors before condemning the ECU

5. Try clearing codes after verifying repairs

💡 Why Repair Instead of Replace?

👉 New OEM ECUs can cost hundreds or even thousands of pounds.
👉 Many failures are repairable at component level — saving time and money.

📍 If you’re in the UK and have a failing ECU, BCMRepair.co.uk specializes in cost-effective, quality ECU repairs with UK-wide support.

They can help with:

• ECU / BCM repair & refurbishment

• Diagnostics and fault tracing

• Fast turnaround & UK postage

✅ Visit BCMRepair.co.uk for more info and accurate repair quotes.