B1801 on Lexus: How to Diagnose & Fix
Lamp Turn Signal Front Output Circuit Short to Ground
1 Lexus model · 1 documented issue · 1 critical
B1801 on Lexus by model: symptoms, diagnosis and fix
An electrical connection inside the steering column's spiral cable assembly — the coiled ribbon that carries signals to the rotating steering wheel — may be insufficiently welded. The connection can separate in service, which deactivates the driver's frontal airbag and puts the vehicle out of compliance with FMVSS 208, Occupant Crash Protection. Critically, campaign 25V040000 targets vehicles that may have been incorrectly repaired under the earlier recall 23V-480, so a car whose records show that prior repair is not necessarily safe. Owner letters were mailed March 17, 2025; the Lexus campaign number is 25LA02.
Common Symptoms
- SRS or airbag warning light illuminated
- Horn does not work
- Steering wheel audio or cruise controls stop responding
- Warning light appears after steering wheel work or a prior recall repair
How to Fix
Do not assume the earlier 23V-480 repair covered this — the entire point of campaign 25V040000 is that some of those repairs were performed incorrectly. Check the VIN with Lexus or NHTSA and have the dealer inspect and replace the spiral cable assembly as necessary, free of charge. Unlike many latent airbag defects, this one usually announces itself: a separated spiral cable typically lights the SRS warning and often disables the horn and the steering wheel controls at the same time, since they share the same ribbon. Treat that combination of symptoms as this recall until proven otherwise, and do not let an independent shop clear the code without replacing the assembly.
Sources for this issue (1)
B1801 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does B1801 mean on a Lexus?
B1801 stands for "Lamp Turn Signal Front Output Circuit Short to Ground." B1801 is a manufacturer-specific body code (most commonly seen on Ford and related makes) indicating the lighting control module detected a short to ground on the front turn-signal lamp output circuit. The module monitors the current it sends to the bulb and flags a fault when that circuit is pulled to ground instead of behaving normally. On other manufacturers this exact code string can mean something different, so the definition should be confirmed against the specific make. The practical effect is usually an inoperative or improperly behaving front turn signal. On Lexus it is documented across 1 model: NX.
What are the most common causes of B1801?
The most common causes of B1801 are: Short to ground in the front turn-signal wiring, Chafed or pinched harness near the front lamp, Corroded or damaged bulb socket/connector, Faulty turn-signal bulb, Water intrusion in the front lamp assembly, Internal fault in the lighting/body control module. The specific cause varies by vehicle.
How much does it cost to fix B1801 on a Lexus?
Repair costs vary widely with the root cause and Lexus model; each issue on this page carries its own estimate where one is published.
Looking for B1801 on a different make?
View B1801 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.