What Does B1666 Mean?
This diagnostic trouble code indicates that the Body Control Module (BCM) or seat control module has detected that the driver's seat recline motor has stalled or stopped operating during commanded movement. The module monitors motor current draw and position feedback, and when the motor fails to move or draws excessive current indicating a mechanical bind or electrical fault, this code is set. This affects the power seat adjustment system specifically related to the seatback recline function.
Common Causes
35%
Mechanical obstruction or binding in seat recline track mechanism due to debris, worn gears, or damaged track components
30%
Faulty seat recline motor with worn brushes, internal short, or seized armature
20%
Wiring harness issues including damaged wires, corroded connectors, or loose connections to recline motor
10%
Failed seat control module or internal driver circuit for recline motor
5%
Insufficient power supply due to weak battery, corroded power distribution connections, or blown fuse
Diagnostic Steps
1
Step 1: Perform visual and physical inspection of driver seat recline mechanism by manually moving seatback through full range of motion, checking for binding, debris, unusual resistance, or grinding noises that indicate mechanical obstruction
2
Step 2: Using a digital multimeter, verify power and ground supply at the seat recline motor connector with ignition on - expect battery voltage (12-14V) on power wire and less than 0.5 ohms resistance to ground on ground circuit
3
Step 3: Disconnect motor connector and measure motor resistance across terminals - typical seat motors show 2-6 ohms resistance; infinite resistance indicates open circuit, near-zero indicates short
4
Step 4: Apply direct battery voltage and ground to motor terminals (bypassing control module) to verify motor operation - motor should run smoothly in both directions when polarity is reversed; if motor runs freely, suspect control module fault
5
Step 5: Inspect seat wiring harness for chafing, pinched wires, or corrosion at connector terminals, paying special attention to areas where harness flexes during seat movement
6
Step 6: If all electrical tests pass and motor operates with direct power, test seat control module outputs using scan tool bidirectional controls while monitoring voltage at motor connector; lack of voltage output confirms module failure
Estimated Repair Cost
$150 - $800
Parts + labor, varies by vehicle and location
This diagnostic trouble code indicates that the Body Control Module (BCM) or seat control module has detected that the driver's seat recline motor has stalled or stopped operating during commanded movement. The module monitors motor current draw and position feedback, and when the motor fails to mov...
The most common cause of B1666 (Seat Driver Recline Motor Stalled) is: Mechanical obstruction or binding in seat recline track mechanism due to debris, worn gears, or damaged track components
Typical repair costs for B1666 range from $150 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving as this does not affect vehicle operation or critical safety systems. The seat recline function will be inoperative, which may affect driver comfort and optimal seating position, but repair can be scheduled at convenience.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1666 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Body
System
Body/Comfort Systems - Power Seat Adjustment
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
