B1555 on 2020-2022 Lincoln Aviator — Tailgate/Liftgate/Boot/Trunk Position Sensor 4 — Signal Invalid (RGTM)
1 vehicles · 1 makes
Most Reported On
B1555 is an OBD-II diagnostic trouble code meaning “Tailgate/Liftgate/Boot/Trunk Position Sensor 4 — Signal Invalid (RGTM).” On power-liftgate vehicles the Rear Gate/Trunk Module (RGTM) sets B1555 when one of the liftgate position-sensor inputs returns an invalid/implausible signal, so the module can no longer trust its picture of where the gate is. Ford's SSM for 2020 Explorer/Aviator lists B1555 with B144D, B144E and B1556 as the code set produced by RGTM software wrongly sensing the liftgate ajar, and also documents B1555 being stored when water intrusion damages the right-hand power liftgate motor. Important scoping note: in Ford's older/legacy body-code list the same number B1555 is published as 'Ignition Run/Start Circuit Failure' for other modules — always read the code with the module that set it. This code is most commonly reported on 2020-2022 Lincoln Aviator.
Common Causes
Diagnostic Tools
B1555 does not use the standard P/B/C/U prefix. It may be a manufacturer-specific code, so verify that a scanner supports your exact year, model and module before buying.
FAQ
What does B1555 mean?
B1555 stands for "Tailgate/Liftgate/Boot/Trunk Position Sensor 4 — Signal Invalid (RGTM)." On power-liftgate vehicles the Rear Gate/Trunk Module (RGTM) sets B1555 when one of the liftgate position-sensor inputs returns an invalid/implausible signal, so the module can no longer trust its picture of where the gate is. Ford's SSM for 2020 Explorer/Aviator lists B1555 with B144D, B144E and B1556 as the code set produced by RGTM software wrongly sensing the liftgate ajar, and also documents B1555 being stored when water intrusion damages the right-hand power liftgate motor. Important scoping note: in Ford's older/legacy body-code list the same number B1555 is published as 'Ignition Run/Start Circuit Failure' for other modules — always read the code with the module that set it.
What are the most common causes of B1555?
The most common causes of B1555 are: Outdated RGTM software (reprogram to latest level per Ford SSM), Water intrusion into the right-hand power liftgate motor/drive unit, Failed liftgate position (Hall-effect) sensor or drive unit, Damaged liftgate wiring harness or corroded connector, Latch/ajar switch fault or misaligned striker. The specific cause varies by vehicle.
How much does it cost to fix B1555?
Repair costs vary widely depending on the root cause and vehicle.
Which vehicles are affected by B1555?
Au7o has documented B1555 across 1 vehicle models from 1 manufacturers: Lincoln.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.