B1672 — Seat Driver Occupied Input Circuit Failure

How do I diagnose B1672 myself?

Start with a scan: confirm B1672, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the seat driver occupied input circuit, and verify the suspect component against live data before buying parts.

What are the symptoms of B1672?

Drivers most often notice: warning light on the dashboard, no impact on engine operation in most cases, the affected function (locks, windows, lighting, wipers) works intermittently or not at all.

What is the most common cause of B1672?

The most common causes are: blown fuse or failed relay, faulty switch, motor or actuator of the affected system, corroded or loose connectors.

Is it safe to drive with B1672?

Usually safe to drive — body codes rarely affect drivability. Exceptions: exterior lighting and wipers in bad weather, and central locking faults that can leave the car unsecured.

What does OBD2 code B1672 mean?

B1672 — Seat Driver Occupied Input Circuit Failure. A fault in the body electrical system. The car is usually drivable while you plan the repair. Typical causes: blown fuse or failed relay, faulty switch, motor or actuator of the affected system, corroded or loose connectors.

When the engine control module detects a problem with the signal that tells the vehicle whether the driver's seat is occupied, it logs trouble code B1672. This circuit is part of the body's electrical architecture — it feeds information to other systems that may rely on knowing whether someone is sitting in the driver's seat, such as airbag deployment logic, seat belt reminders, or certain comfort features. Because the input is faulty, the module cannot trust the data and flags the issue by turning on the check-engine light or a dedicated body-system warning lamp.

The module does not set B1672 based on a single bad reading. Automotive control units are designed to be selective — before lighting the dashboard warning, the PCM or body control module must confirm the fault exists across multiple ignition cycles or under specific voltage and temperature conditions. That deliberate approach prevents false alarms caused by temporary electrical noise or a single glitch. When B1672 is stored, the associated freeze frame data records engine load, RPM, coolant temperature, and vehicle speed at the exact moment the failure was detected. Those values are your roadmap for recreating the problem during testing.

Symptoms of B1672

• The malfunction indicator lamp illuminates on the instrument cluster
• Engine performance and drivability remain unaffected in the vast majority of cases
• One or more body functions operate intermittently or stop working entirely — this may include power locks, windows, interior or exterior lighting, or windshield wipers
• The seat belt reminder may behave erratically if the occupied-status input feeds that system
• In rare cases, adaptive restraint systems default to a safe mode, which may affect airbag readiness indicators
• No change in fuel economy, transmission behavior, or engine responsiveness

Common Causes of B1672

• Corrosion, moisture intrusion, or looseness at electrical connectors in the driver's seat or related body wiring
• Broken or chafed wires, especially in areas that flex repeatedly — door jambs and seat tracks are common failure points
• A blown fuse or a relay that has lost contact due to age or thermal fatigue
• Faulty seat occupancy sensor or the associated pressure switch that feeds the occupied input
• A failing or programming-outdated body control module that misinterprets valid signals as faults
• Water damage from leaks, car washes, or spills that reach wiring or control units in the cabin floor area

How to Diagnose B1672

1. Connect a quality OBD2 scanner and confirm that B1672 is present in the stored codes. Record the freeze frame data before clearing anything — those engine conditions must be replicated during your road test afterward.
2. Look for any pending or permanent codes alongside B1672. Clustered codes in the B-series often point to a shared wiring problem or a single failed module that is causing multiple faults.
3. Perform a thorough visual inspection of the harness and connectors tied to the seat occupancy circuit. Check for cracked insulation, green or white corrosion deposits, and pins that are pushed back or bent.
4. Activate the affected system — power locks, wipers, or whichever function is acting up — and monitor the relevant PID values in live data. Watch for signals that drop out when the door opens or closes, since door harnesses carry many body circuit signals.
5. Pay close attention to flex points: the wiring that passes through the driver's door hinge area and the seat rail connectors suffer the most movement over time. Wiggle the harness while monitoring data to expose intermittent opens.
6. After clearing B1672, drive the vehicle through the conditions captured in the freeze frame — same speed, load, and temperature range — and verify the code does not return within two complete drive cycles.

Repair Options and Costs

The repair approach depends entirely on which component is responsible for the failure. The following are typical parts-and-labor estimates at independent shop rates:

• Wiring repair or connector replacement — $80 to $250. In many cases, cleaning corroded terminals, applying dielectric grease, and reseating a loose plug resolves the issue without any part purchases.
• Seat occupancy sensor or switch replacement — $120 to $450. The specific sensor depends on the vehicle; some cars use a pressure mat under the cushion, others use a Hall-effect switch in the seat rail.
• Body control module repair or replacement — $300 to $900. BCM replacement requires programming or parameter reset, which only a shop with the proper diagnostic platform can perform.

Total cost to repair B1672 typically falls between $80 and $900, depending on which part is at fault. An accurate diagnosis before purchasing components is the single most effective way to keep your bill low — the most expensive scenario should never be your first assumption.

Can You Drive with B1672?

In most vehicles, a seat occupied input failure does not impair engine operation, transmission function, or braking, so driving is generally safe. However, the fault can affect exterior lighting, windshield wipers, or central locking — systems that are directly tied to visibility and vehicle security. If any of those functions are compromised, address the issue before driving in rain, at night, or in areas where unsecured access is a concern. Otherwise, you can continue driving while scheduling repair at your convenience.

The B1672 OBD2 fault code relates to the Climate Control Air Temperature Internal Sensor Motor circuit. When the circuit short to battery, the module cannot properly monitor or control this body system.

At AIscanAuto, we help drivers quickly identify OBD2 trouble codes, understand their root causes, and find the right fix.

Symptoms

• Battery warning light
• Electrical systems losing power
• Possible no-start condition
• Battery drain issues

Common Causes

• Faulty component — internal damage or wear affecting Climate Control Air Temperature Internal Sensor Motor
• Wiring issues — broken, corroded, or chafed wires in the circuit
• Connector problems — loose, oxidized, or moisture-damaged pins
• a short to battery voltage is detected — connects the signal line directly to 12V, causing constant high voltage
• Module input failure — rare, but the control module input stage may be defective

Step-by-Step Diagnosis

1. Scan with OBD2 tool — Confirm B1672 is active. Check for additional DTCs.
2. Visual inspection — Examine the Climate Control Air Temperature Internal Sensor Motor wiring and connector for corrosion or damage.
3. Check voltage and ground — Use a multimeter to verify proper reference voltage.
4. Test component — Compare readings to factory specs. A stuck or erratic signal confirms failure.
5. Check for shorts/opens — Perform continuity tests on the wiring between the component and control module.

Repair & Solutions

• If the component is defective, replace the Climate Control Air Temperature Internal Sensor Motor with an OEM or quality aftermarket part.
• Repair any damaged wiring or connectors using proper methods.
• Clear the DTC with an OBD2 scanner and test drive to verify the code does not return.
• If the code persists after component replacement, inspect the control module connector.

Related Codes

• B1669 — Climate Control Temperature Differential Circuit Short To Ground
• B1670 — Climate Control Air Temperature Internal Sensor Motor Circuit Failure
• B1671 — Climate Control Air Temperature Internal Sensor Motor Circuit Open