Network, generic

U055A Invalid Data Received From Special Purpose Vehicle Control Module A

Check engine lightUsually off

EmissionsNot relevant

Drive cycleNot required

Limp modeNo

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.

Likely causes

Upfitter module programmed or configured for a different vehicle software level

Vehicle modules updated without matching the upfitter module

Poorly made bus connection or splice in the body builder's wiring

Special purpose module A internally faulty

Symptoms

Upfitter equipment (lights, outputs, interlocks) works erratically or not at all
Code stored without warning lamp

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€80–600

Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

special purpose vehicle module a

Related codes

U0259 U055B U055C U055D

References: fordservicecontent.com, content.fordpro.com.