U0056 code meaning
Vehicle Communication Bus D Performance
What U0056 means
U0056 says Vehicle Communication Bus D works, but its traffic is disturbed. Bentley documents it for the Continental GT (2018-20), GTC (2019-20) and Flying Spur (2020): U005600 with symptom numbers 12689537, 12689541 or 12689542 lands in the chassis control unit (address 0074) or in roll control systems 1 and 2 (00D4, 00D5). Bus D is a private CAN there, and its errors pull in a series of suspension codes; the driver sees a red or yellow suspension lamp and a dynamic ride fault message. Bentley has technicians check the connectors and harness of the three units, then update the chassis control software, or replace the unit if it is on another software level. A production change came with a software update. Elsewhere, loose contacts or a resetting node are the usual causes.
U0056 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0056
- Red or yellow suspension warning lamp (Bentley)
- Dynamic ride fault message, several suspension codes stored
- Functions drop out briefly and return
Common causes of U0056
- Most likelyChassis control software level prone to Bus D errors (Bentley)
- PossibleLoose or dirty connector at a module on Bus D
- PossibleDamaged harness between the modules on Bus D
- Less likelyA module on Bus D restarting because of weak supply
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Bus d wiringControl moduleChassis control module
What each part of U0056 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 56 | The exact fault in that area. |
What to do next
- Note U0056 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U0056
What does U0056 mean?
U0056 means "Vehicle Communication Bus D Performance". U0056 says Vehicle Communication Bus D works, but its traffic is disturbed. It is a generic code, so it means the same on every make.
Is it safe to drive with U0056?
Drive gently and only to a workshop. With U0056 the car can go into limp mode (reduced power) to protect itself.
Will U0056 fail an emissions test?
U0056 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U0056 to fix?
Difficulty: hard. A typical repair takes 0.5 to 5 hours of work. This is a job for a workshop.
Will U0056 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.