U055A code meaning
Invalid Data Received From Special Purpose Vehicle Control Module A
What U055A means
Special purpose vehicle control modules are add-on controllers that body builders and upfitters fit to police cars, ambulances, utility trucks and similar conversions. U055A means frames from module A arrive but their content fails the receiver's checks. Ford lists the code in its 2024 OBD operations summary among the powertrain controller's internal plausibility tests and marks it non-MIL for programs carrying a special upfitter module. Ford's 2023 Super Duty shows how such equipment is attached: the factory upfitter integration system passes J1939 signals one way to the body equipment, while the vehicle network itself is encrypted. U0259 is the matching lost-communication code. Expect the upfitter function to misbehave; driving is normally unaffected.
U055A at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U055A
- Upfitter equipment (lights, outputs, interlocks) works erratically or not at all
- Code stored without warning lamp
Common causes of U055A
- Most likelyUpfitter module programmed or configured for a different vehicle software level
- PossibleVehicle modules updated without matching the upfitter module
- PossiblePoorly made bus connection or splice in the body builder's wiring
- Less likelySpecial purpose module A internally faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Special purpose vehicle module a
What each part of U055A means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 5A | The exact fault in that area. |
What to do next
- Note U055A 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 U055A
What does U055A mean?
U055A means "Invalid Data Received From Special Purpose Vehicle Control Module A". Special purpose vehicle control modules are add-on controllers that body builders and upfitters fit to police cars, ambulances, utility trucks and similar conversions. It is a generic code, so it means the same on every make.
Is it safe to drive with U055A?
U055A does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U055A fail an emissions test?
U055A 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 U055A to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will U055A clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.