On many vehicles, Diagnostic Trouble Code B0080 is classified as a Body (B) system code often associated with occupant detection or passenger presence sensing circuits. SAE-style wording treats the code at the system and circuit level rather than naming a guaranteed failed component. Because implementations differ by make, model and year, B0080 requires electrical and network confirmation—power/ground/reference, sensor signal integrity, and plausibility checks—before assuming a sensor or module replacement. Keep diagnosis test-driven: measure, compare to expected values, then confirm repair restores correct readings and clears the fault.
What Does B0080 Mean?
SAE J2012 defines DTC structure and some standardized descriptions; the SAE J2012-DA digital annex publishes the canonical descriptions used for body and chassis codes. Under that framework B0080 is a Body-class trouble code pointing to an occupant detection or passenger presence related circuit condition as interpreted by many OEMs, but the exact component or algorithm tied to the code can vary by manufacturer and year.
The code shown here does not include a hyphen suffix (Failure Type Byte, FTB). If an FTB were present (for example “-1A”), it would identify a subtype such as a specific range, performance, intermittent, or plausibility failure. Without an FTB, B0080 should be treated as a non‑specific circuit/processing indication that needs measurement-based narrowing rather than a definitive part failure.
Quick Reference
- System: Body — occupant detection / passenger presence related circuit
- Failure type: Electrical or plausibility condition (circuit/signal level)
- Primary checks: Power, ground, reference, sensor signal integrity, CAN/communication status
- Common symptom: Occupant classification warnings or airbag disablement depending on vehicle
- Test-driven approach: Measure voltages, resistance, and compare to known-good references
- Interpretation varies by make/model/year — confirm with vehicle-specific service data
Real-World Example / Field Notes
In the shop you may see B0080 stored after a customer reports an airbag or seatbelt reminder irregularity or an illuminated occupant classification warning. A common first observation is that the vehicle’s restraint indicator behaves differently when the seat is occupied versus empty; however, behavior alone is not diagnostic. On several late-model cars the diagnostic tool will show occupant sensor raw values or live data; these scalars often jump erratically or read out-of-range when wiring is corroded or connectors are pushed back under the seat.
One possible cause commonly associated with this code is water intrusion at a seat connector—moisture changes sensor impedance without physically killing the sensor. Another commonly associated cause is a damaged seat harness where chafing near the seat frame produces intermittent opens or shorts when the seat is adjusted. You may also encounter a related case where a control module logs the code after a recent battery disconnect or module swap; in those cases confirm proper wake/sleep behavior, battery voltage stability, and that message traffic for the occupant system appears on the vehicle network.
Field workflow that helps: capture live data while a helper sits in the seat and shifts position, note changes in raw sensor values, wiggle connectors and observe for communication faults, and perform a baseline resistance check across accessible harness segments. Always document the measured values and recheck after any repair or reconnection to ensure the signal stays within expected ranges and the code does not return.
B0080 is reported as a Body Circuit Fault related to occupant sensing circuitry under the SAE J2012-DA framework. Interpretation of B0080 varies by make, model, and year; many chassis and body controllers use different wiring, connectors, or network strategies for occupant detection. Always confirm the fault with basic electrical and Controller Area Network (CAN) testing before assuming a specific component. Use voltage, resistance, continuity, and network-message checks to localize the issue rather than parts replacement by assumption.
Symptoms of B0080
- Warning lamp – Supplemental Restraint System (SRS) or airbag indicator illuminated on dash.
- Occupancy indication – Passenger occupancy or seatbelt/occupant indicator behaves incorrectly or shows unknown status.
- Intermittent – Fault appears and clears intermittently, often with vehicle vibration or seat movement.
- Service message – Cluster or body control module displays a service message related to occupant sensing or airbag readiness.
- Network faults – Multiple body-network warnings or degraded communication events when tested with a scan tool.
- Restraint disabling – Passenger airbag enable/disable logic does not change as expected with different occupant conditions (if applicable).
Common Causes of B0080
Most Common Causes
- Wiring harness damage or connector corrosion in the occupant sensing circuit, commonly associated with seat wiring that moves.
- Poor or missing power/ground to the occupant sensor or body control module input, verified by direct voltage and ground tests.
- Faulty occupant sensor mat or pressure/weight sensor module, noted after resistance/continuity and plausibility checks.
Less Common Causes
- Controller Area Network (CAN) message loss or baud-rate mismatch causing the body module to flag the occupant-sensing circuit.
- Intermittent connector pin contact or module input-stage issue inside a body control module after external tests pass.
- Water intrusion or foreign material in seat cushion sensors causing sporadic readings.
Diagnosis: Step-by-Step Guide
Tools: OBD-II scan tool with live-data and Mode $06, digital multimeter (DMM), backprobe pins, wiring diagrams, oscilloscope (or pico scope), jumper wires, insulated pick tool, and a continuity tester.
- Connect the scan tool, record freeze-frame data and live values for occupant-sensing channels and note any Failure Type Byte (FTB) suffix information.
- Verify stored freeze-frame voltages and timestamps; compare live data while sitting and standing to confirm plausibility of readings.
- Inspect connectors at the seat, occupant sensor, and body control module for corrosion, water, or pin damage; perform wiggle tests while observing live data for intermittent changes.
- With ignition on, use the DMM to check sensor power and ground at the sensor connector. Expect stable battery voltage on power and near-zero ohms to chassis ground on ground circuits.
- Measure signal line voltage and resistance as specified by vehicle documentation; if not available, compare to the companion seat sensor or the known-good channel for plausibility differences.
- Use a continuity tester to check harness integrity between the sensor and the module; repair any open or high-resistance runs before further testing.
- If network-related, monitor Controller Area Network (CAN) bus voltages and data frames with the oscilloscope or a capable scan tool; confirm the module transmits and receives occupant messages.
- When signals look noisy or intermittent, use the oscilloscope to capture waveform shape and timing; look for glitches during seat movement or restart cycles.
- If external wiring, power, and ground test good but the module still reports implausible values, document all tests and consider an input-stage issue in the module as a possible cause.
- Clear codes and re-test after any repair to verify the fault does not return and that live-data shows expected behavior under multiple occupant conditions.
Professional tip: Always quantify failures — record voltages, resistances, and waveform screenshots before and after repairs. If a sensor reading changes only when connectors are flexed, focus on harness repair rather than replacing the sensor or module.
This section lists realistic repairs and cost ranges for a B0080-style body system fault and ties each remedy to the test finding that justifies it. Costs vary by region, vehicle, and labor rates. Always confirm the specific fault with voltage, resistance, continuity, and network message testing before replacing parts. Replace or program control modules only after wiring, power, ground, and signal integrity have been verified with a scope or multimeter and plausibility tests pass.
Possible Fixes & Repair Costs
Low-cost fixes (diagnosis-confirmed wiring or connector repair) — $60 to $180: justified when continuity checks show an open or chafed wire, high-resistance splice, or a loose connector; repair or solder and reseal the connector and re-test. Typical repair (sensor replacement or seat mat module connector service) — $200 to $650: appropriate when bench or live signal tests show a failed sensor or input-stage out of spec, confirmed by measured voltage/current and lack of valid data on the network. High-cost outcome (control module replacement and programming) — $700 to $1,800+: only justified after power/ground/reference and signal wiring test good and the module shows no valid responses, failed internal processing or input-stage issue indicated by scoped traces or vendor diagnostics. Factors affecting cost: access labor, vehicle-specific diagnostics, OEM parts vs aftermarket, and required reprogramming. Always document pre- and post-repair measurements; if a repair fails, that documentation speeds warranty or dealer escalation.
Can I Still Drive With B0080?
You can usually drive with this body-system fault, but it depends on how the vehicle uses occupant sensing data. In many cars the code disables passive functions such as airbag inflation suppression or seatbelt reminders until the fault is cleared or verified safe. If safety systems are limited, you may have reduced protection or warning functionality. Verify with a scan tool whether airbags or restraint warnings are active and take precautions—avoid long trips until diagnosis confirms safe operation.
What Happens If You Ignore B0080?
Ignoring this fault can leave occupant detection or restraint-related features degraded or disabled, which may increase injury risk in a crash and could prevent accurate diagnostic history needed by a shop to repair later. Also, intermittent faults can complicate future diagnosis by altering stored data and masking related failures.
Related Codes
- B0019 – Occupant Restraint Airbag Circuit Fault
- B0018 – Body Circuit Fault — Restraint Sensor Signal
- B0017 – Body Circuit Signal Integrity Fault
- B0016 – Occupant Sensing Circuit Fault (SRS)
- B0014 – Occupant Restraint Circuit Fault
- B0011 – Occupant Restraint Circuit Fault
- B0009 – Restraint System Circuit Fault
- B0008 – Supplemental Restraint System Circuit High
- B0007 – Supplemental Restraint System Circuit Fault
- B0006 – Restraint Deployment Commanded Too Long
Key Takeaways
B0080 is a body-system occupant sensing circuit-level fault and interpretation varies by make/model. Diagnosis must be test-driven: check power, ground, reference, continuity, signal integrity, and network messages. Replace wiring or sensors only when measurements confirm failure. Module replacement is a last step after all external inputs test good. Document all measurements before and after repair for confirmation and warranty support.
Vehicles Commonly Affected by B0080
Commonly seen on modern passenger cars and SUVs from manufacturers such as Toyota, Honda, Ford, and GM, often due to widespread use of seat-occupancy mats, seat belt pretensioner sensors, and distributed body control modules. These platforms frequently use networked occupant-sensing inputs and connector-heavy seat harnesses, so wiring abrasion, connector corrosion, and module input-stage issues are often reported. Interpretation still varies by model and year; confirm with tests.
FAQ
Can a loose connector cause B0080?
Yes. A loose, corroded, or partially seated connector in the seat or body harness can produce intermittent voltage, high resistance, or no signal, triggering a B0080-style circuit fault. Confirm by performing wiggle tests while monitoring live data or signal voltage with a multimeter or oscilloscope, and by checking continuity to the control module. Repair the connector and re-test to verify the fault clears.
Is module replacement often required for B0080?
Module replacement is not often the first step. Only consider replacing a control module after verifying power, ground, reference voltages, wiring continuity, and signal integrity are within spec, and after factory or third-party diagnostics show the module fails to respond or produces invalid bus data. If all external inputs test good and scoped traces indicate internal faults, then module servicing or replacement becomes justified.
How do I know if the seat mat sensor is at fault?
Measure sensor resistance and reference voltage per vehicle-specific service data and observe live occupancy values on a scan tool. A failed mat often shows open/short, no stable reference voltage, or flatlined data on the data bus. Use an oscilloscope to confirm expected waveform or steady-state resistance. Replace the mat only after these measurements clearly indicate sensor failure and wiring tests pass.
Can a network communication issue produce B0080?
Yes. If the body control module or occupant-sensing module cannot exchange valid messages due to CAN bus errors, B0080-like symptoms may appear. Test bus voltage levels, termination resistance, and message presence with a scan tool or bus analyzer. If the bus shows errors or no messages from an expected node, resolve network faults—shorts, high resistance, or missing termination—before changing modules or sensors.
What should a DIY owner check before going to a shop?
Start with simple checks: inspect seat harnesses and connectors for damage, corrosion, or looseness; look for water intrusion or seat cushion deformation. Use a basic scan tool to read live data and note whether occupant data appears; take clear photos of connectors and recorded codes. Provide the shop with those observations and any measured voltages to reduce diagnosis time and avoid unnecessary part replacement.